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-rw-r--r--litmus/Makefile3
-rw-r--r--litmus/sched_edf_hsb.c15
-rw-r--r--litmus/sched_edf_hsb_noslack.c2523
3 files changed, 2534 insertions, 7 deletions
diff --git a/litmus/Makefile b/litmus/Makefile
index 62c2bb064581..9468312b39e4 100644
--- a/litmus/Makefile
+++ b/litmus/Makefile
@@ -18,7 +18,8 @@ obj-y = sched_plugin.o litmus.o \
18 ctrldev.o \ 18 ctrldev.o \
19 servers.o \ 19 servers.o \
20 sched_gsn_edf.o \ 20 sched_gsn_edf.o \
21 sched_edf_hsb.o 21 sched_edf_hsb.o \
22 sched_edf_hsb_noslack.o
22 23
23obj-$(CONFIG_PLUGIN_CEDF) += sched_cedf.o 24obj-$(CONFIG_PLUGIN_CEDF) += sched_cedf.o
24obj-$(CONFIG_PLUGIN_PFAIR) += sched_pfair.o 25obj-$(CONFIG_PLUGIN_PFAIR) += sched_pfair.o
diff --git a/litmus/sched_edf_hsb.c b/litmus/sched_edf_hsb.c
index d89364fdb582..d176efca648b 100644
--- a/litmus/sched_edf_hsb.c
+++ b/litmus/sched_edf_hsb.c
@@ -340,6 +340,9 @@ static noinline void check_donate_slack(server_t *donator, struct task_struct *w
340 340
341 TRACE_SERVER_SUB(donator, "checking donation"); 341 TRACE_SERVER_SUB(donator, "checking donation");
342 342
343 if (!slack)
344 return;
345
343 /* Donating small amounts of slack will result in excess migrations */ 346 /* Donating small amounts of slack will result in excess migrations */
344 if (donator->budget < SLACK_MIN) 347 if (donator->budget < SLACK_MIN)
345 return; 348 return;
@@ -1330,8 +1333,7 @@ static void remove_from_ready(server_t *server, struct task_struct *task,
1330 } 1333 }
1331 } else { 1334 } else {
1332 slack = server_slack(server); 1335 slack = server_slack(server);
1333 BUG_ON(!slack); 1336 if (slack && head_in_list(&slack->list)) {
1334 if (head_in_list(&slack->list)) {
1335 remove_slack(slack); 1337 remove_slack(slack);
1336 } 1338 }
1337 if (server->type == S_BE) { 1339 if (server->type == S_BE) {
@@ -1456,7 +1458,7 @@ static noinline void check_for_slack_preempt(struct task_struct *task,
1456 } 1458 }
1457 1459
1458 /* The server's slack is currently being run */ 1460 /* The server's slack is currently being run */
1459 if (is_server_linked(slack)) { 1461 if (slack && is_server_linked(slack)) {
1460 entry = &per_cpu(cpu_entries, slack->cpu); 1462 entry = &per_cpu(cpu_entries, slack->cpu);
1461 slack_task = server_task(slack); 1463 slack_task = server_task(slack);
1462 1464
@@ -2466,11 +2468,12 @@ static int __init init_edf_hsb(void)
2466 idle_slack = server_alloc(GFP_ATOMIC); 2468 idle_slack = server_alloc(GFP_ATOMIC);
2467 server_init(idle_slack, &server_domain, 2469 server_init(idle_slack, &server_domain,
2468 IDLE_SLACK_BASE + cpu, 2470 IDLE_SLACK_BASE + cpu,
2469 ULLONG_MAX, ULLONG_MAX, 1); 2471 LLONG_MAX, LLONG_MAX, 1);
2470 idle_slack->deadline = ULLONG_MAX; 2472 idle_slack->deadline = LLONG_MAX;
2471 idle_slack->budget = ULLONG_MAX; 2473 idle_slack->budget = LLONG_MAX;
2472 idle_slack->job_no = 1; 2474 idle_slack->job_no = 1;
2473 idle_slack->release = 1; 2475 idle_slack->release = 1;
2476 idle_slack->type = S_SLACK;
2474 add_slack(idle_slack); 2477 add_slack(idle_slack);
2475 2478
2476 entry->cpu = cpu; 2479 entry->cpu = cpu;
diff --git a/litmus/sched_edf_hsb_noslack.c b/litmus/sched_edf_hsb_noslack.c
new file mode 100644
index 000000000000..e6e8d7dd0e8b
--- /dev/null
+++ b/litmus/sched_edf_hsb_noslack.c
@@ -0,0 +1,2523 @@
1/*
2 * litmus/sched_edf_hsb.c
3 *
4 * Implentation of the EDF-HSB scheduling algorithm.
5 *
6 * The following 6 events are fired by timers and not handled by
7 * the plugin infrastructure itself:
8 *
9 * release_[hrt|srt|be]_jobs
10 * [hrt|be]_server_released
11 * server_completed (for HRT, SRT, and BE)
12 *
13 * The following 4 events are caused by a write to the proc entry
14 * and should never be run when the plugin is already running:
15 * stop_[hrt|be]_servers
16 * admit_[hrt|be]_server
17 *
18 * TODO system for removing tasks from their release queues
19 * TODO clean up link_to_cpu and check_slack args
20 * TODO move slack completion into release
21 * TODO fix concurrent arms
22 * TODO slack and BE servers, include slack higher prio
23 * TODO start servers should no longer be cessary
24 * TODO harmonize order of method arguments
25 * TODO test crazy task_new hack
26 * TODO remove bheap_node_in_heap check in litmus_exit_task
27 */
28#include <linux/module.h>
29#include <linux/uaccess.h>
30#include <linux/percpu.h>
31#include <linux/spinlock.h>
32#include <linux/ctype.h>
33#include <linux/sched.h>
34#include <linux/hrtimer.h>
35
36#include <litmus/litmus.h>
37#include <litmus/bheap.h>
38#include <litmus/jobs.h>
39#include <litmus/litmus_proc.h>
40#include <litmus/sched_plugin.h>
41#include <litmus/edf_common.h>
42#include <litmus/sched_trace.h>
43#include <litmus/servers.h>
44#define DEBUG_EDF_HSB
45
46/* DOES NOT WORK */
47//#define SLACK_ON_MASTER
48
49#define BE_PROC_NAME "be_servers"
50#define HRT_PROC_NAME "hrt_servers"
51#define BE_SERVER_BASE 100
52#define IDLE_SLACK_BASE 1000
53#define SLACK_MIN NSEC_PER_MSEC
54
55/* SCHED_TRACE action events */
56#define SERVER_COMPLETED_ACTION 1
57#define SERVER_RELEASED_ACTION 2
58#define NO_SLACK_ACTION 3
59#define SLACK_RUN_ACTION 4
60#define SLACK_STOP_ACTION 5
61#define SLACK_RECLAIM_ACTION 6
62#define SLACK_EXPIRED_ACTION 7
63#define SLACK_DONATED_ACTION 8
64#define CANDIDATE_ADDED_ACTION 9
65
66/* Uncomment for human readable time */
67#define TIME(x) \
68 (x)
69/* ({lt_t y = x; \ */
70/* do_div(y, NSEC_PER_MSEC); \ */
71/* y;}) */
72#define TRACE_TIMER(fmt, args...) \
73 sched_trace_log_message("%d P%d*[%s@%s:%d]: " fmt " at %d\n", \
74 TRACE_ARGS, ## args, TIME(litmus_clock()))
75#define TRACE_TASK_TIMER(t, fmt, args...) \
76 TRACE_TIMER("(%s/%d:%d) " fmt, (t)->comm, (t)->pid, \
77 (t)->rt_param.job_params.job_no, ## args)
78
79/*
80 * Useful debugging macros. Remove for actual use as they cause
81 * a lot of lock contention.
82 */
83#ifdef DEBUG_EDF_HSB
84
85#define TRACE_SUB(fmt, args...) \
86 sched_trace_log_message("%d P%d [%s@%s:%d]: " fmt "\n", \
87 TRACE_ARGS, ## args)
88#define TRACE_TASK_SUB(t, fmt, args...) \
89 TRACE_SUB(TASK_FMT " " fmt, TASK_ARGS(t), ##args)
90#define TRACE_SERVER_SUB(s, fmt, args...) \
91 TRACE_SUB(SERVER_FMT " " fmt, SERVER_ARGS(s), ##args)
92#define TRACE_TASK_SERVER_SUB(t, s, fmt, args...) \
93 TRACE_TASK_SUB(t, SERVER_FMT " " fmt, SERVER_ARGS(s), ##args)
94#else
95#define TRACE_SUB(fmt, args...)
96#define TRACE_TASK_SUB(t, fmt, args...)
97#define TRACE_SERVER_SUB(s, fmt, args...)
98#define TRACE_TASK_SERVER_SUB(t, s, fmt, args...)
99#endif
100
101/*
102 * Different types of servers
103 */
104typedef enum {
105 S_HRT,
106 S_SRT,
107 S_BE,
108 S_SLACK
109} server_type_t;
110
111/*
112 * A server running HRT tasks
113 */
114typedef struct {
115 server_t server;
116 rt_domain_t hrt_domain; /* EDF for HRT tasks assigned here */
117 int ready; /* False if waiting for next release */
118 int no_slack;
119 struct hrtimer slack_timer; /* Server has no slack when:
120 * (deadline - budget) <= current_time.
121 */
122 struct hrtimer_start_on_info slack_timer_info;
123} hrt_server_t;
124
125/*
126 * State of a single CPU
127 */
128typedef struct {
129 int cpu;
130 struct task_struct* scheduled; /* Task that should be running */
131 struct task_struct* linked; /* Task that actually is running */
132 server_t *scheduled_server;
133 server_t *linked_server; /* The server running on this cpu.
134 * Note that what it is 'running' is
135 * linked, not scheduled.
136 */
137 hrt_server_t hrt_server; /* One HRT server per CPU */
138 struct bheap_node* hn; /* For the cpu_heap */
139} cpu_entry_t;
140
141/*
142 * Data assigned to each task
143 */
144typedef struct task_data {
145 server_t *srt_server; /* If the task is SRT, its server */
146 struct list_head candidate_list; /* List of slack canditates */
147 struct task_struct *owner;
148} task_data_t;
149
150/* CPU state */
151DEFINE_PER_CPU_SHARED_ALIGNED(cpu_entry_t, noslack_cpu_entries);
152static struct bheap cpu_heap;
153static struct bheap_node cpu_heap_node[NR_CPUS];
154/* Task domains */
155static rt_domain_t srt_domain;
156static rt_domain_t be_domain;
157/* Useful tools for server scheduling */
158static server_domain_t server_domain;
159/* BE server support */
160static struct list_head be_servers;
161static struct bheap be_ready_servers;
162/* Slack support */
163static struct list_head slack_queue;
164static struct list_head slack_candidates;
165/* CPU which will release tasks and global servers */
166static int edf_hsb_release_master;
167/* Cache to store task_data structs */
168static struct kmem_cache *task_data_cache;
169
170static struct proc_dir_entry *edf_hsb_proc_dir = NULL;
171static struct sched_plugin edf_hsb_plugin __cacheline_aligned_in_smp;
172
173#define task_sched_entry(task) (&per_cpu(noslack_cpu_entries, task_cpu(task)))
174#define task_linked_entry(task) (&per_cpu(noslack_cpu_entries, task->rt_param.linked_on))
175#define task_job_no(task) (tsk_rt(task)->job_params.job_no)
176#define task_data(task) ((task_data_t*)tsk_rt(task)->plugin_data)
177#define task_srt_server(task) ((server_t*)task_data(task)->srt_server)
178#define server_slack(s) ((server_t*)(s)->data)
179#define server_has_slack(s) (server_slack(s)->deadline != 0)
180#define local_cpu_entry (&__get_cpu_var(noslack_cpu_entries))
181#define global_lock (&srt_domain.ready_lock)
182#define is_active_plugin (litmus == &edf_hsb_plugin)
183
184/*
185 * This only works if items are deleted with list_del_init.
186 */
187static inline int head_in_list(struct list_head *head)
188{
189 BUG_ON(!head);
190 return !(head->next == head->prev && head->prev == head);
191}
192
193/*
194 * Returns slack server running the task or NULL if N/A.
195 */
196static inline server_t* task_slack_server(struct task_struct *task)
197{
198 server_t *slack_server = NULL;
199 if (task->rt_param.linked_on != NO_CPU) {
200 slack_server = task_linked_entry(task)->linked_server;
201 if (slack_server->type != S_SLACK)
202 slack_server = NULL;
203 }
204 return slack_server;
205}
206
207static task_data_t* task_data_alloc(int gfp_flags)
208{
209 return kmem_cache_alloc(task_data_cache, gfp_flags);
210}
211
212static void task_data_free(task_data_t* data)
213{
214 kmem_cache_free(task_data_cache, data);
215}
216
217/*
218 * Donating servers pre-allocate a server for slack to avoid runtime
219 * calls to kmalloc.
220 */
221static void server_slack_create(server_t *donator)
222{
223 server_t *slack = server_alloc(GFP_ATOMIC);
224
225 server_init(slack, &server_domain, -donator->id, 0, 0, 1);
226 slack->type = S_SLACK;
227 slack->data = donator;
228 donator->data = slack;
229}
230
231
232static void server_slack_destroy(server_t *donator)
233{
234 server_t *slack = (server_t*)donator->data;
235
236 donator->data = NULL;
237 server_destroy(slack);
238 server_free(slack);
239}
240
241static void remove_slack(server_t *slack)
242{
243 if (!slack)
244 return;
245 TRACE_SERVER_SUB(slack, "slack removed");
246 //sched_trace_action(NULL, SLACK_EXPIRED_ACTION);
247
248 if (head_in_list(&slack->list))
249 list_del_init(&slack->list);
250 slack->deadline = 0;
251 slack->budget = 0;
252 slack->wcet = 0;
253}
254
255/*
256 * Slack queue is EDF.
257 */
258static void add_slack(server_t *slack)
259{
260 struct list_head *pos;
261 server_t *queued;
262
263 TRACE_SERVER_SUB(slack, "slack added");
264
265 if (head_in_list(&slack->list))
266 return;
267
268 list_for_each_prev(pos, &slack_queue) {
269 queued = list_entry(pos, server_t, list);
270 if (lt_before_eq(queued->deadline, slack->deadline)) {
271 __list_add(&slack->list, pos, pos->next);
272 return;
273 }
274 }
275 list_add(&slack->list, &slack_queue);
276}
277
278static inline struct task_struct* get_candidate(struct list_head *pos)
279{
280 struct task_struct *task = NULL;
281 task_data_t *data;
282 if (!list_empty(pos)) {
283 data = list_entry(pos, task_data_t, candidate_list);
284 task = data->owner;
285 }
286 return task;
287}
288
289/*
290 * Candidate queue is EDF.
291 */
292static void add_slack_candidate(struct task_struct *task)
293{
294 struct list_head *pos;
295 struct task_struct *queued;
296
297 TRACE_TASK_SUB(task, "candidate added");
298
299 list_for_each_prev(pos, &slack_candidates) {
300 queued = get_candidate(pos);
301 if (lt_before_eq(get_deadline(queued), get_deadline(task))) {
302 __list_add(&task_data(task)->candidate_list,
303 pos, pos->next);
304 return;
305 }
306 }
307 list_add(&task_data(task)->candidate_list, &slack_candidates);
308}
309
310static void donate_slack(server_t *donator)
311{
312 server_t *slack = (server_t*)donator->data;
313 hrt_server_t *hrt_server;
314
315 TRACE_SERVER_SUB(donator, "%llu slack donated", TIME(donator->budget));
316
317 if (donator->type == S_HRT) {
318 hrt_server = container_of(donator, hrt_server_t, server);
319 BUG_ON(!hrt_server->ready);
320 }
321
322 BUG_ON(head_in_list(&slack->list));
323
324 slack->wcet = donator->budget;
325 slack->budget = donator->budget;
326 slack->deadline = donator->deadline;
327
328 add_slack(slack);
329}
330
331#if 0
332/*
333 * Donate any available slack from a server.
334 */
335static noinline void check_donate_slack(server_t *donator, struct task_struct *was_scheduled)
336{
337 server_t *slack = server_slack(donator);
338 hrt_server_t *hrt_server;
339 int donate = 0;
340
341 TRACE_SERVER_SUB(donator, "checking donation");
342
343 /* Donating small amounts of slack will result in excess migrations */
344 if (donator->budget < SLACK_MIN)
345 return;
346
347 if (server_has_slack(donator)) {
348 TRACE_SERVER_SUB(donator, "dead: %d, rel: %d, job: %d already donated",
349 slack->deadline, slack->release, slack->job_no);
350 return;
351 }
352
353 if (donator->type == S_HRT)
354 hrt_server = container_of(donator, hrt_server_t, server);
355
356 /* Donate if the server is waiting for a task release */
357 if ((donator->type == S_SRT &&
358 donator->job_no <= task_job_no(was_scheduled)) ||
359 (donator->type == S_HRT &&
360 hrt_server->no_slack && hrt_server->ready &&
361 !__jobs_pending(&hrt_server->hrt_domain)) ||
362 (donator->type == S_BE &&
363 !__jobs_pending(&be_domain))) {
364 donate = 1;
365 }
366
367 if (!donate)
368 return;
369
370 sched_trace_action(was_scheduled, SLACK_DONATED_ACTION);
371
372 donate_slack(donator);
373}
374
375#else
376#define check_donate_slack(a, b)
377#endif
378
379/*
380 * Adds the task to the candidate queue if it is eligible for slack stealing.
381 */
382static void check_slack_candidate(struct task_struct *task)
383{
384 TRACE_TASK_SUB(task, "checking for candidate");
385 if (is_srt(task) &&
386 /* The task has been synchronously released */
387 task_job_no(task) > 2 &&
388 /* The SRT task is behind its server */
389 task_srt_server(task)->job_no > task_job_no(task) &&
390 /* The task hasn't already been added to the list */
391 !head_in_list(&task_data(task)->candidate_list)) {
392
393 add_slack_candidate(task);
394 }
395}
396
397/*
398 * Returns the next eligible slack server. This will remove any expired
399 * slack servers still present in the list.
400 */
401static noinline server_t* next_eligible_slack_server(void)
402{
403 server_t *next_slack = NULL;
404
405 while (!list_empty(&slack_queue)) {
406 next_slack = list_entry(slack_queue.next, server_t, list);
407 BUG_ON(!next_slack);
408
409 if (lt_after(next_slack->deadline, litmus_clock()) &&
410 lt_after(next_slack->budget, SLACK_MIN) &&
411 !is_server_linked(next_slack)) {
412 break;
413 } else {
414 /* Slack has expired or has too little time */
415 remove_slack(next_slack);
416 next_slack = NULL;
417 }
418 }
419
420 return next_slack;
421}
422
423/*
424 * Returns the next SRT task that is tardy or will be tardy. If none
425 * are available, will return a tardy BE task if present.
426 */
427static noinline struct task_struct* next_eligible_slack(void)
428{
429 struct task_struct *next = get_candidate(slack_candidates.next);
430
431 /* We couldn't find an SRT to schedule. Find a BE which is
432 * either tardy or cannot run due to a lack of servers.
433 */
434 if (!next) {
435 next = __peek_ready(&be_domain);
436 }
437 return next;
438}
439
440/*
441 * Order BE tasks FIFO.
442 */
443static inline int be_higher_prio(struct task_struct *first, struct task_struct *second)
444{
445 return lt_before(get_release(first), get_release(second)) ||
446
447 /* Break by PID */
448 (get_release(first) == get_release(second) &&
449 (first->pid < second->pid));
450}
451
452static int be_ready_order(struct bheap_node *a, struct bheap_node *b)
453{
454 struct task_struct *first, *second;
455 first = bheap2task(a);
456 second = bheap2task(b);
457 if (!first || !second)
458 return first && !second;
459 return be_higher_prio(first, second);
460}
461
462/*
463 * Order servers by EDF.
464 */
465static inline int server_higher_prio(server_t *first, server_t *second)
466{
467 return lt_before(first->deadline, second->deadline) ||
468 /* Break by id */
469 (first->deadline == second->deadline &&
470 first->id < second->id);
471}
472
473static int server_order(struct bheap_node *a, struct bheap_node *b)
474{
475 server_t *first, *second;
476 first = a->value;
477 second = b->value;
478 return server_higher_prio(first, second);
479}
480
481/*
482 * Order CPU's by deadlines of their servers.
483 */
484static int cpu_lower_prio(struct bheap_node *a, struct bheap_node *b)
485{
486 cpu_entry_t *first, *second;
487 first = a->value;
488 second = b->value;
489 if (first->linked && second->linked) {
490 return !server_higher_prio(first->linked_server,
491 second->linked_server);
492 }
493 return second->linked && !first->linked;
494}
495
496/*
497 * Move the CPU entry to the correct position in the queue.
498 */
499static inline void update_cpu_position(cpu_entry_t *entry)
500{
501 if (likely(bheap_node_in_heap(entry->hn)))
502 bheap_delete(server_order, &cpu_heap, entry->hn);
503 /* Don't leave HRT CPUs in the heap as its order only matters
504 * for global preempts.
505 */
506 if (!entry->linked || !is_hrt(entry->linked))
507 bheap_insert(cpu_lower_prio, &cpu_heap, entry->hn);
508}
509
510static inline cpu_entry_t* lowest_prio_cpu(void)
511{
512 struct bheap_node *hn = bheap_peek(cpu_lower_prio, &cpu_heap);
513 return (hn) ? hn->value : NULL;
514}
515
516static inline int check_hrt_server_initialized(hrt_server_t *hrt_server)
517{
518 return hrt_server->server.wcet && hrt_server->server.period;
519}
520
521/*
522 * Arms the slack timer for the server, if necessary.
523 */
524static void slack_timer_arm(hrt_server_t *hrt_server)
525{
526 int cpu, err;
527 cpu_entry_t *entry;
528 struct hrtimer *timer;
529 lt_t now = litmus_clock(), when_to_fire;
530
531 if (!check_hrt_server_initialized(hrt_server)) {
532 TRACE_SERVER_SUB(&hrt_server->server, "not initialized");
533 return;
534 }
535
536 timer = &hrt_server->slack_timer;
537 entry = container_of(hrt_server, cpu_entry_t, hrt_server);
538
539#ifdef SLACK_ON_MASTER
540 if (edf_hsb_release_master != NO_CPU)
541 cpu = edf_hsb_release_master;
542 else
543#endif
544 cpu = entry->cpu;
545
546 when_to_fire = hrt_server->server.deadline - hrt_server->server.budget;
547
548 /* Ensure the timer is needed */
549 if (hrtimer_active(timer) || hrt_server->server.deadline == 0 ||
550 hrt_server->no_slack || hrt_server->server.budget == 0 ||
551 !hrt_server->ready) {
552 TRACE_SERVER_SUB(&hrt_server->server,
553 "not arming slack timer on P%d, %d %d %d %d %d",
554 entry->cpu,
555 hrtimer_active(timer), hrt_server->server.deadline == 0,
556 hrt_server->no_slack, hrt_server->server.budget == 0,
557 !hrt_server->ready);
558 return;
559 }
560
561 if (when_to_fire >= hrt_server->server.deadline) {
562 TRACE_SUB("wtf: %llu, dead: %llu, bud: %llu",
563 when_to_fire, hrt_server->server.deadline,
564 hrt_server->server.budget);
565 BUG_ON(1);
566 }
567
568 /* Arm timer */
569 if (lt_after_eq(now, when_to_fire)) {
570 /* 'Fire' immediately */
571 TRACE_SERVER_SUB(&hrt_server->server,
572 "immediate: %llu", when_to_fire);
573 hrt_server->no_slack = 1;
574 } else if (cpu != smp_processor_id()) {
575 err = hrtimer_start_on(cpu,
576 &hrt_server->slack_timer_info,
577 &hrt_server->slack_timer,
578 ns_to_ktime(when_to_fire),
579 HRTIMER_MODE_ABS_PINNED);
580 if (err)
581 TRACE_SERVER_SUB(&hrt_server->server, "failed to arm slack");
582 } else {
583 __hrtimer_start_range_ns(timer, ns_to_ktime(when_to_fire),
584 0, HRTIMER_MODE_ABS_PINNED, 0);
585 }
586
587 TRACE_SUB("slack timer 0x%x armed to fire at %llu on P%d",
588 timer, TIME(when_to_fire), entry->cpu);
589}
590
591/*
592 * Does nothing if the slack timer is not armed.
593 */
594static inline void slack_timer_cancel(hrt_server_t *hrt_server)
595{
596 int ret;
597 if (hrtimer_active(&hrt_server->slack_timer)) {
598 ret = hrtimer_try_to_cancel(&hrt_server->slack_timer);
599 if (ret == -1) {
600 TRACE_SERVER_SUB(&hrt_server->server,
601 "slack timer was running concurrently");
602 } else {
603 TRACE_SERVER_SUB(&hrt_server->server,
604 "slack timer cancelled");
605 }
606 } else {
607 TRACE_SERVER_SUB(&hrt_server->server, "slack not active");
608 }
609}
610
611/*
612 * Handles subtraction of lt_t without underflows.
613 */
614static inline lt_t lt_subtract(lt_t a, lt_t b)
615{
616 long long sub = (long long)a - (long long)b;
617 if (sub >= 0)
618 return sub;
619 else
620 return 0;
621}
622
623static void requeue_server(server_t *server, lt_t now)
624{
625 int added = 0;
626 hrt_server_t *hrt_server;
627
628 if (server->type == S_SRT || server->type == S_SLACK)
629 return;
630
631 if (lt_before(now, server->release)) {
632 added = add_server_release(server, &server_domain);
633 }
634
635 if (!added) {
636 /* Mark servers as released */
637 if (server->type == S_HRT) {
638 TRACE_SERVER_SUB(server, "P%d now ready at %llu", now);
639 hrt_server = container_of(server, hrt_server_t, server);
640 hrt_server->ready = 1;
641 remove_slack(server_slack(server));
642 hrt_server->no_slack = 0;
643 sched_trace_action(NULL, SERVER_RELEASED_ACTION);
644 } else if (server->type == S_BE) {
645 TRACE_SERVER_SUB(server, "BE added to ready");
646 bheap_insert(server_order, &be_ready_servers, server->hn);
647 }
648 } else {
649 BUG_ON(bheap_node_in_heap(server->hn));
650 }
651}
652
653/*
654 * Absorbs a task's execution time into its donator.
655 */
656static void reclaim_slack(server_t *slack)
657{
658 lt_t exec;
659 server_t *donator = server_slack(slack);
660
661 if (!donator)
662 return;
663
664 /* SRT servers do not ever reclaim slack */
665 sched_trace_action(NULL, SLACK_RECLAIM_ACTION);
666
667 exec = slack->wcet - slack->budget;
668 TRACE_SERVER_SUB(donator, "reclaiming %llu slack", TIME(exec));
669
670 BUG_ON(is_server_linked(donator));
671 BUG_ON(!slack->wcet);
672 BUG_ON(!donator->budget);
673
674 donator->budget = lt_subtract(donator->budget, exec);
675 slack->wcet = slack->budget;
676
677 /* If budget exhausted, server needs to wait for next release */
678 if (!donator->budget) {
679 TRACE_SERVER_SUB(donator, "exhausted by slack");
680 }
681}
682
683/*
684 * Begins server execution and arms any timers necessary.
685 */
686static noinline void link_server(cpu_entry_t *entry,
687 server_t *next_server)
688{
689
690 if (entry->linked) {
691 /* Massive state check */
692 if (next_server->type == S_SRT) {
693 /* SRT task cannot get ahead of its server */
694 BUG_ON(next_server->job_no + 1 < task_job_no(entry->linked));
695 BUG_ON(lt_after(get_deadline(entry->linked),
696 next_server->deadline));
697 BUG_ON(head_in_list(&task_data(entry->linked)->candidate_list));
698 } else if (next_server->type == S_HRT) {
699 /* HRT servers should never, ever migrate */
700 BUG_ON(entry->cpu != task_cpu(entry->linked));
701 BUG_ON(!entry->hrt_server.ready);
702 } else if (next_server->type == S_SLACK) {
703 /* Should have already been removed from slack list */
704 BUG_ON(head_in_list(&task_data(entry->linked)->candidate_list));
705 BUG_ON(is_be(entry->linked) && is_queued(entry->linked));
706 sched_trace_action(entry->linked, SLACK_RUN_ACTION);
707 } else { /* BE */
708 /* Should have already been removed from ready heap */
709 BUG_ON(bheap_node_in_heap(next_server->hn));
710 BUG_ON(is_queued(entry->linked));
711 sched_trace_action(entry->linked, next_server->id);
712 }
713
714 if (next_server->type != S_SLACK &&
715 (head_in_list(&server_slack(next_server)->list))) {
716 remove_slack(server_slack(next_server));
717 }
718
719 entry->linked_server = next_server;
720 server_run(entry->linked_server, entry->linked);
721 }
722
723 /* Timer necessary whenever an HRT is not running */
724 if (!entry->linked || !is_hrt(entry->linked))
725 slack_timer_arm(&entry->hrt_server);
726 else
727 slack_timer_cancel(&entry->hrt_server);
728}
729
730/*
731 * Stops server execution and timers. This will also re-add servers
732 * to any collections they should be members of.
733 */
734static noinline void unlink_server(cpu_entry_t *entry, int requeue)
735{
736 server_t *server = entry->linked_server;
737 hrt_server_t *hrt_server = &entry->hrt_server;
738
739 BUG_ON(!entry->linked_server);
740
741 server_stop(entry->linked_server);
742 server = entry->linked_server;
743 entry->linked_server = NULL;
744
745 if (!requeue)
746 return;
747
748 if (server->type == S_SLACK && server->deadline) {
749 add_slack(server);
750 sched_trace_action(entry->linked, SLACK_STOP_ACTION);
751
752 /* Donator needs to absorb slack execution time */
753 reclaim_slack(server);
754 } else if (server->type != S_SRT) {
755 requeue_server(server, litmus_clock());
756 }
757
758 if (server->type == S_HRT && hrt_server->ready)
759 BUG_ON(head_in_list(&server_slack(server)->list));
760}
761
762static void requeue(struct task_struct *task, rt_domain_t *domain);
763static inline rt_domain_t* get_rt_domain(cpu_entry_t *entry, struct task_struct *task);
764
765/* Update the link of a CPU.
766 * Handles the case where the to-be-linked task is already
767 * scheduled on a different CPU. The last argument is only needed
768 * for BE tasks as their servers can't be determined here.
769 */
770static noinline void link_to_cpu(cpu_entry_t *entry,
771 struct task_struct* linked,
772 server_t* next_server)
773{
774 cpu_entry_t *sched;
775 server_t *tmp_server;
776 struct task_struct *tmp_task;
777 int on_cpu;
778
779 BUG_ON(linked && !is_realtime(linked));
780 BUG_ON(linked && is_hrt(linked) && entry->cpu != task_cpu(linked));
781 BUG_ON(entry->cpu == edf_hsb_release_master);
782
783 if (linked)
784 TRACE_TASK_SERVER_SUB(linked, next_server, "linking to P%d",
785 entry->cpu);
786
787 /* Currently linked task is set to be unlinked. */
788 if (entry->linked) {
789 unlink_server(entry, 1);
790 entry->linked->rt_param.linked_on = NO_CPU;
791 entry->linked = NULL;
792 }
793
794 /* Link new task to CPU. */
795 if (linked) {
796 set_rt_flags(linked, RT_F_RUNNING);
797 /* Handle task is already scheduled somewhere! */
798 on_cpu = linked->rt_param.scheduled_on;
799 if (on_cpu != NO_CPU) {
800 sched = &per_cpu(noslack_cpu_entries, on_cpu);
801 /* This should only happen if not linked already */
802 BUG_ON(sched->linked == linked);
803
804 if (entry != sched &&
805 sched->linked && is_hrt(sched->linked)) {
806 /* We are already scheduled on a CPU with an HRT */
807 TRACE_TASK_SUB(linked,
808 "cannot move to scheduled CPU P%d",
809 sched->cpu);
810
811 requeue_server(next_server, litmus_clock());
812 requeue(linked, get_rt_domain(entry, linked));
813
814 linked = NULL;
815 next_server = NULL;
816 } else if (entry != sched) {
817 /* Link to the CPU we are scheduled on by swapping
818 * with that CPU's linked task.
819 */
820 BUG_ON(is_hrt(linked));
821
822 TRACE_TASK_SUB(linked,"already scheduled on P%d",
823 sched->cpu);
824
825 tmp_task = sched->linked;
826 tmp_server = sched->linked_server;
827
828 if (tmp_task)
829 unlink_server(sched, 0);
830
831 linked->rt_param.linked_on = sched->cpu;
832 sched->linked = linked;
833 link_server(sched, next_server);
834
835 update_cpu_position(sched);
836
837 linked = tmp_task;
838 next_server = tmp_server;
839 }
840 }
841 if (linked) /* Might be NULL due to swap */
842 linked->rt_param.linked_on = entry->cpu;
843 }
844 entry->linked = linked;
845 link_server(entry, next_server);
846 update_cpu_position(entry);
847
848 BUG_ON(!entry->linked && entry->linked_server);
849
850 if (linked)
851 TRACE_TASK_SERVER_SUB(linked, next_server,
852 "linked to %d", entry->cpu);
853 else
854 TRACE_SUB("NULL linked to %d", entry->cpu);
855}
856
857/*
858 * Grab the local HRT or global SRT or BE domain for the task.
859 */
860static inline rt_domain_t* get_rt_domain(cpu_entry_t *entry,
861 struct task_struct *task)
862{
863 if (is_hrt(task))
864 return &entry->hrt_server.hrt_domain;
865 else if (is_srt(task))
866 return &srt_domain;
867 else /* BE */
868 return &be_domain;
869}
870
871/*
872 * Ensures the task is not linked anywhere nor present in any ready queues.
873 */
874static noinline void unlink(struct task_struct* t)
875{
876 cpu_entry_t *entry;
877
878 BUG_ON(!t);
879
880 if (t->rt_param.linked_on != NO_CPU) {
881 /* Unlink */
882 entry = task_linked_entry(t);
883 link_to_cpu(entry, NULL, NULL);
884 } else if (is_queued(t)) {
885
886 if (head_in_list(&task_data(t)->candidate_list)) {
887 list_del_init(&task_data(t)->candidate_list);
888 }
889
890 entry = task_sched_entry(t);
891
892 /* A task that is unlinked due to a slack server must be treated
893 * differently. It is probably queued in a release_queue, but
894 * a race condition could allow is_released() to return true
895 * even when the task has not yet been released. Attempting
896 * to remove the task in this case would be disastrous.
897 */
898 if (entry->scheduled == t &&
899 entry->scheduled_server && /* Can be NULL on task_new */
900 entry->scheduled_server->type == S_SLACK) {
901
902 TRACE_TASK_SUB(t, "unlinked on slack server");
903
904 } else if (is_released(t, litmus_clock())) {
905 /* This is an interesting situation: t is scheduled,
906 * but has already been unlinked. It was re-added to
907 * a ready queue of some sort but now needs to
908 * be removed. This usually happens when a job has
909 * been preempted but completes before it is
910 * descheduled.
911 */
912 TRACE_TASK_SUB(t, "removing from domain");
913 remove(get_rt_domain(entry, t), t);
914 BUG_ON(is_queued(t));
915 }
916 }
917}
918
919/*
920 * A job generated by a HRT task is eligible if either the job's deadline
921 * is earlier than the server's next deadline, or the server has zero slack
922 * time in its current period.
923 */
924static inline int is_eligible(struct task_struct *task,
925 hrt_server_t *hrt_server)
926{
927 TRACE_TASK_SUB(task, "%d %d %llu %llu",
928 hrt_server->ready, hrt_server->no_slack,
929 hrt_server->server.deadline,
930 get_deadline(task));
931 return hrt_server->ready && !is_server_linked(&hrt_server->server) &&
932 (hrt_server->no_slack ||
933 lt_after_eq(hrt_server->server.deadline, get_deadline(task)));
934}
935
936/*
937 * Set the server to release at the closest preceding deadline to time.
938 */
939static inline void catchup_server(server_t *server, lt_t time)
940{
941 lt_t diff, sub;
942
943 diff = time - server->deadline;
944 sub = diff % server->period;
945
946 server_release_at(server, time - sub);
947 TRACE_SERVER_SUB(server, "catching up to %llu", time);
948}
949
950static noinline int catchup_srt_server(struct task_struct *task)
951{
952 int jobs, rv = 0;
953 lt_t release;
954 lt_t now = litmus_clock();
955 server_t *srt_server = task_srt_server(task);
956
957 if (lt_before(srt_server->deadline, now) &&
958 srt_server->job_no > 1) {
959 /* Calculate the number of jobs behind the server is */
960 jobs = lt_subtract(now, srt_server->deadline) /
961 srt_server->period + 1;
962
963 /* Get the new release */
964 release = srt_server->release + jobs * srt_server->period;
965
966 TRACE_SERVER_SUB(srt_server, "catching up to %llu, job %d",
967 release, srt_server->job_no + jobs);
968
969 BUG_ON(jobs < 1);
970
971 /* Update server state */
972 server_release_at(srt_server, release);
973 srt_server->job_no += jobs - 1;
974
975 /* Force task to take characteristics of server */
976 tsk_rt(task)->job_params.release = srt_server->release;
977 tsk_rt(task)->job_params.deadline = srt_server->deadline;
978
979 rv = 1;
980
981 sched_trace_action(task, SERVER_RELEASED_ACTION);
982
983 } else if (lt_before(srt_server->deadline, now) &&
984 srt_server->job_no <= 1) {
985
986 server_release_at(srt_server, get_release(task));
987 srt_server->job_no = task_job_no(task);
988 }
989
990 BUG_ON(srt_server->job_no == 0);
991
992 return rv;
993}
994
995/*
996 * If the server is eligible, return the next eligible job. If the server is
997 * ineligible or there are no eligible jobs, returns NULL. This will re-release
998 * any servers that are behind.
999 */
1000static noinline struct task_struct* next_eligible_hrt(hrt_server_t *hrt_server)
1001{
1002 lt_t now = litmus_clock();
1003 lt_t dead, slack, budget;
1004 struct task_struct *task = __peek_ready(&hrt_server->hrt_domain);
1005
1006 /* Catch up server if it is initialized, not running, and late */
1007 if (check_hrt_server_initialized(hrt_server) &&
1008 !is_server_linked(&hrt_server->server)) {
1009
1010 dead = hrt_server->server.deadline;
1011 budget = hrt_server->server.budget;
1012 slack = lt_subtract(dead, budget);
1013
1014 TRACE_SERVER_SUB(&hrt_server->server, "dead: %llu, budget: %llu"
1015 "now: %llu, slack: %llu",
1016 TIME(dead), TIME(budget), TIME(now), TIME(slack));
1017
1018 if (!head_in_list(&hrt_server->server.release_list) &&
1019 lt_before_eq(dead, now)) {
1020 /* The server missed a release */
1021 catchup_server(&hrt_server->server, now);
1022 TRACE_SERVER_SUB(&hrt_server->server, "now ready");
1023 hrt_server->ready = 1;
1024 remove_slack(server_slack(&hrt_server->server));
1025 hrt_server->no_slack = 0;
1026
1027 slack = lt_subtract(hrt_server->server.deadline,
1028 hrt_server->server.budget);
1029
1030 sched_trace_action(task, SERVER_RELEASED_ACTION);
1031 }
1032
1033 /* If the slack timer is active, this is not necessary */
1034 if (!hrtimer_active(&hrt_server->slack_timer) && hrt_server->ready) {
1035 if (lt_before_eq(slack, now) && !hrt_server->no_slack) {
1036 /* The server missed the shift to no slack */
1037 TRACE_SERVER_SUB(&hrt_server->server, "no slack: %llu",
1038 TIME(slack));
1039 hrt_server->no_slack = 1;
1040 sched_trace_action(task, NO_SLACK_ACTION);
1041 } else {
1042 slack_timer_arm(hrt_server);
1043 }
1044 }
1045
1046 } else {
1047 TRACE_SERVER_SUB(&hrt_server->server, "%llu %d %llu %d %d",
1048 hrt_server->server.deadline,
1049 is_server_linked(&hrt_server->server),
1050 now, check_hrt_server_initialized(hrt_server),
1051 !is_server_linked(&hrt_server->server));
1052 }
1053
1054 if (!hrt_server->server.budget ||
1055 (task && !is_eligible(task, hrt_server))) {
1056
1057 if (!hrt_server->server.budget &&
1058 !head_in_list(&hrt_server->server.release_list)) {
1059 TRACE_SERVER_SUB(&hrt_server->server, "requeing");
1060 catchup_server(&hrt_server->server, now);
1061 requeue_server(&hrt_server->server, now);
1062 slack_timer_arm(hrt_server);
1063 }
1064
1065 if (task) {
1066 TRACE_TASK_SUB(task, "not eligible, budget: %llu",
1067 TIME(hrt_server->server.budget));
1068 }
1069 task = NULL;
1070
1071 /* Donate slack if we have nothing to schedule */
1072 if (hrt_server->ready && hrt_server->no_slack) {
1073 check_donate_slack(&hrt_server->server, NULL);
1074 }
1075 }
1076
1077 return task;
1078}
1079
1080/*
1081 * This will catch up the SRT's server if it is behind.
1082 */
1083static noinline struct task_struct* next_eligible_srt(void)
1084{
1085 int done = 0;
1086 struct task_struct *next_srt;
1087
1088 while (!done) {
1089 next_srt = __peek_ready(&srt_domain);
1090
1091 /* A blocking task might pollute the SRT domain if the
1092 * task blocked while it was being run by a slack server.
1093 * Remove and ignore this task.
1094 */
1095 while (next_srt && (get_rt_flags(next_srt) == RT_F_BLOCK ||
1096 unlikely(!is_realtime(next_srt)))) {
1097 TRACE_TASK_SUB(next_srt, "removing finished task");
1098 remove(&srt_domain, next_srt);
1099 next_srt = __peek_ready(&srt_domain);
1100 }
1101
1102 /* If the task blocked for awhile or has otherwise not been
1103 * accessed, its server could have fallen behind.
1104 */
1105 if (next_srt) {
1106 done = !catchup_srt_server(next_srt);
1107
1108 /* The parameters were modified. Re-insert the task. */
1109 if (!done) {
1110 remove(&srt_domain, next_srt);
1111 __add_ready(&srt_domain, next_srt);
1112 } else if (is_server_linked(task_srt_server(next_srt))){
1113 remove(&srt_domain, next_srt);
1114 done = 0;
1115 }
1116 } else {
1117 done = 1;
1118 }
1119 }
1120
1121 return next_srt;
1122}
1123
1124static inline server_t* next_be_server(void)
1125{
1126 struct bheap_node *hn = bheap_peek(server_order, &be_ready_servers);
1127 return (hn) ? hn->value : NULL;
1128}
1129
1130static noinline server_t* next_eligible_be_server(void)
1131{
1132 server_t *be_server = next_be_server();
1133 lt_t now = litmus_clock();
1134
1135 /* Catch up any late be servers. This happens when the servers could
1136 * not find tasks to schedule or if the system is overutilized.
1137 */
1138 while (be_server && (lt_before_eq(be_server->deadline, now) ||
1139 is_server_linked(be_server))) {
1140 if (!be_server->deadline) {
1141 TRACE_SERVER_SUB(be_server, "not intialized");
1142 return NULL;
1143 }
1144 bheap_delete(server_order, &be_ready_servers,
1145 be_server->hn);
1146
1147 if (is_server_linked(be_server)) {
1148 TRACE_SERVER_SUB(be_server, "linked");
1149 continue;
1150 }
1151
1152 catchup_server(be_server, now);
1153 check_donate_slack(be_server, NULL);
1154 bheap_insert(server_order, &be_ready_servers,
1155 be_server->hn);
1156 be_server = next_be_server();
1157 TRACE_SERVER_SUB(be_server, "catching up BE server");
1158 sched_trace_action(NULL, SERVER_RELEASED_ACTION); /* Release */
1159 }
1160
1161 if (be_server && lt_before(now, be_server->release)) {
1162 TRACE_SERVER_SUB(be_server, "not released");
1163 be_server = NULL;
1164 }
1165
1166 if (be_server) {
1167 TRACE_SERVER_SUB(be_server, "dead: %llu, rel: %llu, budget: %llu",
1168 be_server->deadline, be_server->release,
1169 be_server->budget);
1170
1171 }
1172
1173 return be_server;
1174}
1175
1176/*
1177 * Adds a task to the appropriate queue (ready / release) in a domain.
1178 */
1179static noinline void requeue(struct task_struct *task, rt_domain_t *domain)
1180{
1181 lt_t now = litmus_clock();
1182 int was_added;
1183
1184 BUG_ON(!is_realtime(task));
1185 if (head_in_list(&task_data(task)->candidate_list)) {
1186 list_del_init(&task_data(task)->candidate_list);
1187 }
1188
1189 check_slack_candidate(task);
1190
1191 if (is_queued(task)) {
1192 TRACE_TASK_SUB(task, "not requeueing, already queued");
1193 } else if (is_released(task, now)) {
1194 TRACE_TASK_SUB(task, "requeuing on ready %llu %llu %llu %llu",
1195 get_release(task), get_deadline(task),
1196 get_rt_period(task), now);
1197 __add_ready(domain, task);
1198 } else {
1199 /* Task needs to wait until it is released */
1200 TRACE_TASK_SUB(task, "requeuing on release");
1201
1202 was_added = add_release(domain, task);
1203
1204 /* The release time happened before we added ourselves
1205 * to the heap. We can now add to ready.
1206 */
1207 if (!was_added) {
1208 TRACE_TASK_SUB(task, "missed release, going to ready");
1209 __add_ready(domain, task);
1210 }
1211 }
1212}
1213
1214static inline void earlier_server_task(server_t *first,
1215 struct task_struct *first_task,
1216 server_t *second,
1217 struct task_struct *second_task,
1218 server_t **server,
1219 struct task_struct **task)
1220{
1221 if (!first ||
1222 (second && lt_before_eq(second->deadline, first->deadline))) {
1223 *server = second;
1224 *task = second_task;
1225 } else {
1226 *server = first;
1227 *task = first_task;
1228 }
1229}
1230
1231/*
1232 * Set server and task to the next server and task respectively.
1233 * If entry is not null, the next server will see if it can schedule
1234 * entry's linked task.
1235 */
1236static void next_global_task(cpu_entry_t *entry,
1237 server_t **next_server,
1238 struct task_struct **next_task)
1239{
1240 struct task_struct *next_srt, *next_be, *next_slack;
1241 server_t *be_server, *slack_server, *srt_server;
1242
1243 *next_server = NULL;
1244 *next_task = NULL;
1245
1246 next_srt = next_eligible_srt();
1247 srt_server = (next_srt) ? task_srt_server(next_srt) : NULL;
1248
1249 next_be = __peek_ready(&be_domain);
1250 be_server = next_eligible_be_server();
1251
1252 next_slack = next_eligible_slack();
1253 slack_server = next_eligible_slack_server();
1254
1255 TRACE_SUB("be_server: %d, next_be: %d, next_srt: %d, slack_server: %d "
1256 "next_slack: %d", (be_server) ? be_server->id : -1,
1257 (next_be) ? next_be->pid : -1,
1258 (next_srt) ? next_srt->pid : -1,
1259 (slack_server) ? slack_server->id : -1,
1260 (next_slack) ? next_slack->pid : -1);
1261
1262 /* Check if the servers can schedule the task linked to entry */
1263 if (entry && entry->linked) {
1264
1265 if (entry->linked_server->type == S_BE &&
1266 (!next_be ||
1267 lt_before(get_release(entry->linked),
1268 get_release(next_be)))) {
1269
1270 next_be = entry->linked;
1271 } else if (entry->linked_server->type == S_SLACK &&
1272 (!next_slack ||
1273 lt_before(get_deadline(entry->linked),
1274 get_deadline(next_slack)))) {
1275
1276 next_slack = entry->linked;
1277 }
1278 }
1279
1280 /* Remove tasks without servers and vice versa from contention */
1281 if (!next_be || !be_server) {
1282 next_be = NULL;
1283 be_server = NULL;
1284 }
1285 if (!next_slack || !slack_server) {
1286 next_slack = NULL;
1287 slack_server = NULL;
1288 }
1289
1290 /* Favor BE servers. If we don't, then a BE server might lose
1291 * out to its own slack.
1292 */
1293 if (slack_server && be_server &&
1294 be_server->deadline == slack_server->deadline) {
1295 next_slack = NULL;
1296 slack_server = NULL;
1297 }
1298
1299 /* There is probably a better way to do this */
1300 earlier_server_task(srt_server, next_srt,
1301 be_server, next_be,
1302 next_server, next_task);
1303 earlier_server_task(*next_server, *next_task,
1304 slack_server, next_slack,
1305 next_server, next_task);
1306
1307 //BUG_ON(*next_server && lt_before(litmus_clock(), *next_server->release));
1308}
1309
1310/*
1311 * Remove the task and server from any ready queues.
1312 */
1313static void remove_from_ready(server_t *server, struct task_struct *task,
1314 cpu_entry_t *entry)
1315{
1316 server_t *slack;
1317 rt_domain_t *domain;
1318 BUG_ON(!server);
1319 BUG_ON(!entry);
1320 BUG_ON(!task);
1321
1322 if (server->type == S_SLACK) {
1323 TRACE_SERVER_SUB(server, "removed from slack list");
1324 list_del_init(&server->list);
1325
1326 /* Remove from consideration of BE servers */
1327 if (is_be(task) && is_queued(task)) {
1328 TRACE_TASK_SUB(task, "BE removed from ready");
1329 remove(&be_domain, task);
1330 }
1331 } else {
1332 slack = server_slack(server);
1333 if (slack && head_in_list(&slack->list)) {
1334 remove_slack(slack);
1335 }
1336 if (server->type == S_BE) {
1337 TRACE_SERVER_SUB(server, "server removed from ready");
1338 BUG_ON(!server->hn);
1339 bheap_delete(server_order, &be_ready_servers,
1340 server->hn);
1341 }
1342 if (is_queued(task)) {
1343 domain = get_rt_domain(entry, task);
1344 BUG_ON(!domain);
1345 TRACE_TASK_SUB(task, "removed from ready");
1346 remove(domain, task);
1347 }
1348 }
1349
1350 BUG_ON(!task_data(task));
1351
1352 /* Remove from consideration of slack servers */
1353 if (head_in_list(&task_data(task)->candidate_list)) {
1354 TRACE_TASK_SUB(task, "deleting candidate");
1355 list_del_init(&task_data(task)->candidate_list);
1356 }
1357
1358}
1359
1360static void check_for_slack_preempt(struct task_struct*,server_t*,cpu_entry_t*, int);
1361
1362/*
1363 * Finds and links the next server and task to an entry with no linked task.
1364 */
1365static void edf_hsb_pick_next(cpu_entry_t *entry)
1366{
1367 struct task_struct *next_task, *linked;
1368 server_t *next_server;
1369
1370 BUG_ON(entry->linked);
1371
1372 next_task = next_eligible_hrt(&entry->hrt_server);
1373 if (next_task)
1374 next_server = &entry->hrt_server.server;
1375 else
1376 next_global_task(NULL, &next_server, &next_task);
1377
1378
1379 if (next_task) {
1380 remove_from_ready(next_server, next_task, entry);
1381 check_for_slack_preempt(next_task, next_server, entry, 1);
1382 TRACE_TASK_SERVER_SUB(next_task, next_server,
1383 "removing and picked");
1384
1385 /* A slack preemption could cause something that was already
1386 * running to be 'swapped' to this CPU in link_to_cpu.
1387 */
1388 if (entry->linked) {
1389 linked = entry->linked;
1390 unlink(entry->linked);
1391 requeue(linked, get_rt_domain(entry, linked));
1392 TRACE_TASK_SUB(linked, "preempted next pick");
1393 }
1394 link_to_cpu(entry, next_task, next_server);
1395 }
1396}
1397
1398/*
1399 * Preempt the currently running server and task with new ones.
1400 * It is possible that either only the server or the task is different here.
1401 */
1402static void preempt(cpu_entry_t *entry, struct task_struct *next,
1403 server_t *next_server, int slack_resched)
1404{
1405 struct task_struct *linked;
1406 rt_domain_t *domain;
1407
1408 TRACE_TASK_SERVER_SUB(next, next_server,
1409 "preempting on P%d", entry->cpu);
1410
1411 remove_from_ready(next_server, next, entry);
1412
1413 check_for_slack_preempt(next, next_server, entry, slack_resched);
1414 linked = entry->linked;
1415 link_to_cpu(entry, next, next_server);
1416
1417 /* No need for this if only the server was preempted */
1418 if (!linked || linked != entry->linked) {
1419 if (linked) {
1420 domain = get_rt_domain(entry, linked);
1421 requeue(linked, domain);
1422 }
1423 preempt_if_preemptable(entry->scheduled, entry->cpu);
1424 }
1425}
1426
1427/*
1428 * Causes a preemption if:
1429 * 1. task is being run by a slack server on a different CPU
1430 * 2. slack donated by server is running a task on a different CPU
1431 */
1432static noinline void check_for_slack_preempt(struct task_struct *task,
1433 server_t *server,
1434 cpu_entry_t *next_entry,
1435 int resched)
1436{
1437 cpu_entry_t *entry = NULL;
1438 server_t *slack = server_slack(server);
1439 struct task_struct *slack_task;
1440
1441 /* The task is currently being run by another slack server */
1442 if (tsk_rt(task)->linked_on != NO_CPU) {
1443 entry = task_linked_entry(task);
1444
1445 if (entry != next_entry) {
1446 TRACE_TASK_SUB(task, "was on P%d", entry->cpu);
1447
1448 unlink(task);
1449
1450 if (resched) {
1451 edf_hsb_pick_next(entry);
1452 preempt_if_preemptable(entry->scheduled, entry->cpu);
1453 }
1454 }
1455 }
1456
1457 /* The server's slack is currently being run */
1458 if (slack && is_server_linked(slack)) {
1459 entry = &per_cpu(noslack_cpu_entries, slack->cpu);
1460 slack_task = server_task(slack);
1461
1462 unlink(slack_task);
1463 remove_slack(slack);
1464 requeue(slack_task, get_rt_domain(entry, slack_task));
1465
1466 if (entry != next_entry && resched) {
1467 TRACE_SERVER_SUB(slack, "was on P%d", entry->cpu);
1468 /* Force a reschedule */
1469 edf_hsb_pick_next(entry);
1470 preempt_if_preemptable(entry->scheduled, entry->cpu);
1471 } else {
1472 /* This can only happen on a preemption. If a preemption
1473 * happens, the task will be requeued elsewhere.
1474 * Obviously the next task has already been chosen.
1475 */
1476 TRACE_SERVER_SUB(slack, "was on local P%d", entry->cpu);
1477 }
1478 }
1479}
1480
1481/*
1482 * Check for any necessary non-hrt preemptions.
1483 */
1484static void check_for_global_preempt(void)
1485{
1486 cpu_entry_t *entry, *sched;
1487 server_t *next_server;
1488 int on_cpu;
1489 struct task_struct *next_task = (struct task_struct*)1; /* Not NULL */
1490
1491 for (entry = lowest_prio_cpu(); entry; entry = lowest_prio_cpu()) {
1492 /* HRT cpus should not be in this heap */
1493 BUG_ON(entry->linked && is_hrt(entry->linked));
1494
1495 next_global_task(entry, &next_server, &next_task);
1496
1497 if (!next_server)
1498 break;
1499
1500 /* Preempt only if we have an earlier deadline */
1501 if (entry->linked &&
1502 !lt_before(next_server->deadline,
1503 entry->linked_server->deadline)) {
1504 break;
1505 }
1506
1507 /* If we are scheduled on another CPU, the link code
1508 * will force us to link to that CPU and try and link
1509 * that CPU's task to this CPU. This is impossible
1510 * if that CPU has linked HRT tasks which cannot
1511 * migrate.
1512 */
1513 on_cpu = next_task->rt_param.scheduled_on;
1514 if (on_cpu != NO_CPU) {
1515 sched = &per_cpu(noslack_cpu_entries, on_cpu);
1516
1517 if (sched != entry && sched->linked &&
1518 is_hrt(sched->linked)) {
1519
1520 TRACE_TASK_SUB(next_task,
1521 "Already on P%d",
1522 sched->cpu);
1523 break;
1524 }
1525 }
1526
1527 /* We do not reschedule if this causes a slack preemption
1528 * because we will detect if we should reschedule on the
1529 * next iteration of the loop.
1530 */
1531 preempt(entry, next_task, next_server,
1532 0 /* Don't reschedule on a slack preemption */);
1533 }
1534}
1535
1536/*
1537 * Correct local link after a change to the local HRT domain.
1538 */
1539static void check_for_hrt_preempt(cpu_entry_t *entry)
1540{
1541 hrt_server_t *hrt_server = &entry->hrt_server;
1542 struct task_struct *next_hrt = next_eligible_hrt(hrt_server);
1543
1544 if (next_hrt &&
1545 (!entry->linked || !is_hrt(entry->linked) ||
1546 !is_eligible(entry->linked, hrt_server) ||
1547 edf_preemption_needed(&hrt_server->hrt_domain, entry->linked))) {
1548
1549 preempt(entry, next_hrt, &hrt_server->server, 1);
1550
1551 } else {
1552 TRACE_SERVER_SUB(&hrt_server->server, "not HRT preempting");
1553 }
1554}
1555
1556/*
1557 * Assumes called with local irqs disabled.
1558 */
1559static void job_arrival(struct task_struct *task, cpu_entry_t *entry)
1560{
1561 int was_empty;
1562
1563 BUG_ON(task_cpu(task) == NO_CPU);
1564
1565 TRACE_TASK_SUB(task, "arriving on P%d", entry->cpu);
1566
1567 if (is_hrt(task)) {
1568 requeue(task, &entry->hrt_server.hrt_domain);
1569 check_for_hrt_preempt(entry);
1570 } else if (is_srt(task)) {
1571 requeue(task, &srt_domain);
1572 check_for_global_preempt();
1573 } else /* BE */ {
1574 was_empty = !__jobs_pending(&be_domain);
1575 requeue(task, &be_domain);
1576
1577 /* Only way this could cause a preemption is if an eligible
1578 * BE server could not queue up a task.
1579 */
1580 if (was_empty && __jobs_pending(&be_domain))
1581 check_for_global_preempt();
1582 }
1583}
1584
1585/******************************************************************************
1586 * Timer methods
1587 ******************************************************************************/
1588
1589/*
1590 * Merges a group of released HRT tasks into a ready queue and checks
1591 * for preeemptions.
1592 */
1593static void release_hrt_jobs(rt_domain_t *domain, struct bheap *tasks)
1594{
1595 unsigned long flags;
1596 struct task_struct *first;
1597 cpu_entry_t *entry;
1598
1599 raw_spin_lock_irqsave(global_lock, flags);
1600
1601 first = (struct task_struct*)bheap_peek(edf_ready_order, tasks)->value;
1602 entry = task_sched_entry(first);
1603
1604 BUG_ON(!first || !is_hrt(first));
1605 TRACE_TASK(first, "HRT tasks released at %llu on P%d\n",
1606 TIME(litmus_clock()), task_cpu(first));
1607
1608 __merge_ready(domain, tasks);
1609 check_for_hrt_preempt(entry);
1610
1611 raw_spin_unlock_irqrestore(global_lock, flags);
1612}
1613
1614/*
1615 * Merges a group of released tasks into a ready queue and checks to see
1616 * if scheduled needs to be called.
1617 */
1618static void release_srt_jobs(rt_domain_t *domain, struct bheap *tasks)
1619{
1620 unsigned long flags;
1621 struct task_struct *first = (bheap_peek(edf_ready_order, tasks)->value);
1622
1623 raw_spin_lock_irqsave(global_lock, flags);
1624
1625 TRACE_TASK(first, "SRT tasks released at %llu\n", TIME(litmus_clock()));
1626
1627 __merge_ready(domain, tasks);
1628 check_for_global_preempt();
1629
1630 raw_spin_unlock_irqrestore(global_lock, flags);
1631}
1632
1633/*
1634 * Merges a group of released tasks into a ready queue and checks to see
1635 * if scheduled needs to be called.
1636 */
1637static void release_be_jobs(rt_domain_t *domain, struct bheap *tasks)
1638{
1639 unsigned long flags;
1640 int was_empty;
1641 struct task_struct *first = (bheap_peek(edf_ready_order, tasks)->value);
1642
1643 TRACE_TASK(first, "BE tasks released at %llu\n", TIME(litmus_clock()));;
1644
1645 raw_spin_lock_irqsave(global_lock, flags);
1646
1647 was_empty = !__jobs_pending(domain);
1648 __merge_ready(domain, tasks);
1649 if (was_empty) {
1650 /* Only way this could cause a preemption is if an BE server
1651 * could not find a task to run.
1652 */
1653 check_for_global_preempt();
1654 }
1655
1656 raw_spin_unlock_irqrestore(global_lock, flags);
1657}
1658
1659static enum hrtimer_restart slack_timer_fire(struct hrtimer *timer)
1660{
1661 unsigned long flags;
1662 hrt_server_t *server = container_of(timer, hrt_server_t, slack_timer);
1663 cpu_entry_t *entry = container_of(server, cpu_entry_t, hrt_server);
1664
1665 raw_spin_lock_irqsave(global_lock, flags);
1666
1667 TRACE_TIMER("slack timer fired for P%d", entry->cpu);
1668 BUG_ON(!server->ready);
1669 sched_trace_action(entry->linked, NO_SLACK_ACTION);
1670
1671 /* Set new state of entry */
1672 server->no_slack = 1;
1673 check_for_hrt_preempt(entry);
1674
1675 /* Donate slack if the HRT server cannot run anything */
1676 if (!entry->linked || !is_hrt(entry->linked)) {
1677 check_donate_slack(&server->server, NULL);
1678 check_for_global_preempt();
1679 }
1680
1681 raw_spin_unlock_irqrestore(global_lock, flags);
1682
1683 return HRTIMER_NORESTART;
1684}
1685
1686static void job_completion(cpu_entry_t *entry, struct task_struct* task)
1687{
1688 server_t *server = entry->linked_server;
1689 set_rt_flags(task, RT_F_SLEEP);
1690
1691 TRACE_TASK_SUB(task, "completed");
1692
1693 unlink(task);
1694 check_donate_slack(server, task);
1695
1696 /* If a slack server completed an SRT task, the work for the
1697 * next job arrival has already been done.
1698 */
1699 if (server->type == S_SLACK && is_srt(task)) {
1700 tsk_rt(task)->job_params.job_no++;
1701 sched_trace_task_release(task);
1702 TRACE_TASK_SERVER_SUB(task, server, "catching up SRT, "
1703 "rel: %llu, dead: %llu",
1704 TIME(get_release(task)),
1705 TIME(get_deadline(task)));
1706 check_slack_candidate(task);
1707 sched_trace_task_completion(task, 1);
1708
1709 return;
1710 }
1711
1712 BUG_ON(is_queued(task));
1713
1714 if (server->type == S_SRT) {
1715 /* If the task is behind the server it must release immediately,
1716 * leaving its release time and deadline unchanged.
1717 */
1718 if (server->job_no > tsk_rt(task)->job_params.job_no) {
1719 TRACE_TASK_SUB(task, "catching up");
1720 tsk_rt(task)->job_params.job_no++;
1721 } else {
1722 /* Otherwise release them both */
1723 prepare_for_next_period(task);
1724 TRACE_TASK_SUB(task, "next release: %llu, dead: %llu",
1725 TIME(get_release(task)),
1726 TIME(get_deadline(task)));
1727 server_release(server);
1728 }
1729 } else {
1730 prepare_for_next_period(task);
1731 TRACE_TASK_SUB(task, "next release: %llu, dead: %llu",
1732 TIME(get_release(task)),
1733 TIME(get_deadline(task)));
1734 }
1735
1736 if (is_released(task, litmus_clock()))
1737 sched_trace_task_release(task);
1738
1739 /* Don't requeue a blocking task */
1740 if (is_running(task))
1741 job_arrival(task, entry);
1742
1743 sched_trace_task_completion(task, 1);
1744}
1745
1746/*
1747 * Assumes called with local irqs disabled.
1748 */
1749static void server_completed(server_t *server, struct task_struct *task)
1750{
1751 hrt_server_t *hrt_server;
1752 cpu_entry_t *entry = task_linked_entry(task);
1753
1754 BUG_ON(entry->linked != task);
1755 BUG_ON(entry->linked_server != server);
1756
1757 if (server->type == S_SRT) {
1758 TRACE_TASK_SUB(task, "must wait on server");
1759
1760 /* The job must now take the priority and release time
1761 * of the next server. We do this so that we can still
1762 * use rt_domain and other handy methods to still work
1763 * with SRT jobs. Because this can ONLY happen if the
1764 * task's job number gets behind the server's, we can
1765 * easily detect the job catching up later.
1766 */
1767 tsk_rt(task)->job_params.release = server->deadline;
1768 tsk_rt(task)->job_params.deadline = server->deadline +
1769 get_rt_period(task);
1770 TRACE_TASK_SUB(task, "waiting, new dead: %llu, new rel: %llu",
1771 TIME(get_deadline(task)),
1772 TIME(get_release(task)));
1773
1774 } else if (server->type == S_HRT) {
1775 /* Update state of HRT server */
1776 hrt_server = container_of(server, hrt_server_t, server);
1777 hrt_server->ready = 0;
1778 TRACE_SERVER_SUB(server, "P%d no longer ready", entry->cpu);
1779
1780 if (hrtimer_active(&hrt_server->slack_timer))
1781 slack_timer_cancel(hrt_server);
1782 }
1783
1784 if (server->type != S_SLACK) {
1785 server_release(server);
1786 sched_trace_action(task, SERVER_COMPLETED_ACTION);
1787 }
1788
1789 unlink(task);
1790 requeue(task, get_rt_domain(entry, task));
1791
1792 /* We know this CPU needs to pick its next task */
1793 edf_hsb_pick_next(entry);
1794
1795 /* Only cause a reschedule if something new was scheduled. A task
1796 * could merely have swapped servers.
1797 */
1798 if (entry->linked != task)
1799 preempt_if_preemptable(entry->scheduled, entry->cpu);
1800 else
1801 entry->scheduled_server = entry->linked_server;
1802}
1803
1804static void hrt_server_released(server_t *server)
1805{
1806 hrt_server_t *hrt_server = container_of(server, hrt_server_t, server);
1807 cpu_entry_t *entry = container_of(hrt_server, cpu_entry_t, hrt_server);
1808
1809 BUG_ON(hrtimer_active(&hrt_server->slack_timer));
1810 TRACE_SERVER_SUB(server, "HRT server released on P%d", entry->cpu);
1811
1812 hrt_server->no_slack = 0;
1813 hrt_server->ready = 1;
1814 remove_slack(server_slack(&hrt_server->server));
1815
1816 check_for_hrt_preempt(entry);
1817
1818 /* Ensure slack timer is only running if the current
1819 * job is not HRT.
1820 */
1821 if (entry->linked && is_hrt(entry->linked))
1822 slack_timer_cancel(hrt_server);
1823 else
1824 slack_timer_arm(hrt_server);
1825}
1826
1827static void servers_released(struct list_head *servers)
1828{
1829 int was_be = 0;
1830 unsigned long flags;
1831 struct list_head *pos, *safe;
1832 server_t *server;
1833
1834 raw_spin_lock_irqsave(global_lock, flags);
1835
1836 sched_trace_action(NULL, SERVER_RELEASED_ACTION);
1837 TRACE_TIMER("Servers released");
1838
1839 list_for_each_safe(pos, safe, servers) {
1840 server = list_entry(pos, server_t, release_list);
1841
1842 list_del_init(pos);
1843
1844 if (server->type == S_BE) {
1845 check_donate_slack(server, NULL);
1846 was_be = 1;
1847 BUG_ON(bheap_node_in_heap(server->hn));
1848 TRACE_SERVER_SUB(server, "inserting BE server");
1849 bheap_insert(server_order, &be_ready_servers,
1850 server->hn);
1851 check_donate_slack(server, NULL);
1852 } else { /* HRT server */
1853 hrt_server_released(server);
1854 }
1855 }
1856
1857 if (was_be)
1858 check_for_global_preempt();
1859
1860 raw_spin_unlock_irqrestore(global_lock, flags);
1861}
1862
1863/******************************************************************************
1864 * Server management methods
1865 ******************************************************************************/
1866
1867static int curr_be = 0;
1868
1869/*
1870 * A BE server has been added in a proc entry.
1871 */
1872static int admit_be_server(unsigned long long wcet,
1873 unsigned long long period,
1874 int cpu)
1875{
1876 int rv = 0;
1877 server_t *be_server;
1878
1879 if (cpu != NO_CPU) {
1880 rv = -EINVAL;
1881 goto out;
1882 }
1883
1884 be_server = server_alloc(GFP_ATOMIC);
1885 server_init(be_server, &server_domain,
1886 BE_SERVER_BASE + ++curr_be,
1887 wcet, period, 1);
1888 be_server->type = S_BE;
1889 server_slack_create(be_server);
1890
1891 TRACE_SERVER_SUB(be_server, "admitted BE server");
1892
1893 list_add(&be_server->list, &be_servers);
1894 bheap_insert(server_order, &be_ready_servers, be_server->hn);
1895
1896 out:
1897 return rv;
1898}
1899
1900/*
1901 * Output all BE servers to a proc entry.
1902 */
1903static void list_be_servers(server_proc_t *proc)
1904{
1905 struct list_head *pos;
1906 server_t *be_server;
1907
1908 list_for_each(pos, &be_servers) {
1909 be_server = list_entry(pos, server_t, list);
1910 list_server(be_server, NO_CPU, proc);
1911 }
1912}
1913
1914/*
1915 * Halts and destroys all BE servers.
1916 */
1917static void stop_be_servers(void)
1918{
1919 server_t *be_server;
1920 struct list_head *pos, *safe;
1921
1922 list_for_each_safe(pos, safe, &be_servers) {
1923 be_server = list_entry(pos, server_t, list);
1924
1925 list_del_init(pos);
1926 if (bheap_node_in_heap(be_server->hn))
1927 bheap_delete(server_order, &be_ready_servers,
1928 be_server->hn);
1929 server_slack_destroy(be_server);
1930 server_destroy(be_server);
1931 server_free(be_server);
1932 }
1933}
1934
1935/*
1936 * An HRT server has been added in a proc entry.
1937 */
1938static int admit_hrt_server(unsigned long long wcet,
1939 unsigned long long period,
1940 int cpu)
1941{
1942 cpu_entry_t *entry = &per_cpu(noslack_cpu_entries, cpu);
1943 hrt_server_t *hrt_server = &entry->hrt_server;
1944 struct hrtimer *slack_timer = &hrt_server->slack_timer;
1945
1946 server_init(&hrt_server->server, &server_domain,
1947 cpu, wcet, period, 1);
1948 server_slack_create(&hrt_server->server);
1949 hrt_server->no_slack = 0;
1950 hrt_server->ready = 1;
1951 hrt_server->server.type = S_HRT;
1952
1953 edf_domain_init(&hrt_server->hrt_domain, NULL,
1954 release_hrt_jobs);
1955
1956 hrtimer_init(slack_timer,
1957 CLOCK_MONOTONIC,
1958 HRTIMER_MODE_ABS);
1959 slack_timer->function = slack_timer_fire;
1960
1961 return 0;
1962}
1963
1964/*
1965 * Print all HRT servers to a proc entry.
1966 */
1967static void list_hrt_servers(server_proc_t *proc)
1968{
1969 cpu_entry_t *entry;
1970 hrt_server_t *hrt_server;
1971 int cpu;
1972
1973 for_each_online_cpu(cpu) {
1974 entry = &per_cpu(noslack_cpu_entries, cpu);
1975 hrt_server = &entry->hrt_server;
1976 list_server(&hrt_server->server, cpu, proc);
1977 }
1978}
1979
1980/*
1981 * Stops all hrt server timers and resets all fields to 0.
1982 */
1983static void stop_hrt_servers(void)
1984{
1985 int cpu;
1986 cpu_entry_t *entry;
1987 hrt_server_t *hrt_server;
1988
1989 for_each_online_cpu(cpu) {
1990 entry = &per_cpu(noslack_cpu_entries, cpu);
1991 hrt_server = &entry->hrt_server;
1992
1993 if (hrt_server->server.data)
1994 server_slack_destroy(&hrt_server->server);
1995 slack_timer_cancel(hrt_server);
1996
1997 hrt_server->no_slack = 0;
1998 hrt_server->ready = 0;
1999 hrt_server->server.period = 0;
2000 hrt_server->server.wcet = 0;
2001 }
2002}
2003
2004/*
2005 * Starts timers used to manage servers.
2006 */
2007static void start_servers(lt_t time)
2008{
2009 int cpu;
2010 cpu_entry_t *entry;
2011 server_t *server;
2012 server_t *be_server;
2013 struct list_head *pos;
2014
2015 TRACE_SUB("starting servers at %llu", time);
2016
2017 /* Start HRT servers */
2018 for_each_online_cpu(cpu) {
2019 entry = &per_cpu(noslack_cpu_entries, cpu);
2020 server = &entry->hrt_server.server;
2021
2022 if (!check_hrt_server_initialized(&entry->hrt_server))
2023 goto loop_end;
2024
2025 /* Cause a catchup later */
2026 server_release_at(server, time - server->period);
2027 entry->hrt_server.ready = 1;
2028
2029 TRACE("Setting up cpu %d to have timer deadline %llu\n",
2030 cpu, TIME(server->deadline));
2031 loop_end:
2032 cpu = cpu;
2033 }
2034
2035 /* Start BE servers */
2036 list_for_each(pos, &be_servers) {
2037 be_server = list_entry(pos, server_t, list);
2038
2039 if (!bheap_node_in_heap(be_server->hn))
2040 bheap_insert(server_order, &be_ready_servers, be_server->hn);
2041
2042 /* Cause a catchup later */
2043 server_release_at(be_server, time - be_server->period);
2044
2045 TRACE("Releasing BE server %d\n", be_server->id);
2046 TRACE_SERVER_SUB(be_server, "inserting be server");
2047 }
2048}
2049
2050/******************************************************************************
2051 * Plugin methods
2052 ******************************************************************************/
2053
2054static long edf_hsb_activate_plugin(void)
2055{
2056 int cpu;
2057 cpu_entry_t *entry;
2058#ifdef CONFIG_RELEASE_MASTER
2059 edf_hsb_release_master = atomic_read(&release_master_cpu);
2060#else
2061 edf_hsb_release_master = NO_CPU;
2062#endif
2063 server_domain.release_master = edf_hsb_release_master;
2064
2065 for_each_online_cpu(cpu) {
2066 entry = &per_cpu(noslack_cpu_entries, cpu);
2067#ifdef CONFIG_RELEASE_MASTER
2068 if (cpu != edf_hsb_release_master)
2069#endif
2070 update_cpu_position(entry);
2071 }
2072
2073 start_servers(litmus_clock());
2074
2075 TRACE("activating EDF-HSB plugin.\n");
2076 return 0;
2077}
2078
2079/*
2080 * Requires a processor be specified for any task run on the system.
2081 */
2082static long edf_hsb_admit_task(struct task_struct *task)
2083{
2084 cpu_entry_t *entry = task_sched_entry(task);
2085
2086 TRACE_TASK(task, "Admitting\n");
2087
2088 if (is_hrt(task)) {
2089 return check_hrt_server_initialized(&entry->hrt_server) &&
2090 ((task_cpu(task) == task->rt_param.task_params.cpu) &&
2091 (task_cpu(task) == entry->cpu)) ? 0 : -EINVAL;
2092 } else {
2093 /* If the task is not HRT, we don't want to force the user
2094 * to specify a CPU.
2095 */
2096 return 0;
2097 }
2098}
2099
2100/*
2101 * Stops all servers from running.
2102 */
2103static long edf_hsb_deactivate_plugin(void)
2104{
2105 cpu_entry_t *cpu_entry;
2106 hrt_server_t *hrt_server;
2107 unsigned long flags;
2108 int cpu;
2109
2110 local_irq_save(flags);
2111
2112 for_each_online_cpu(cpu) {
2113 cpu_entry = &per_cpu(noslack_cpu_entries, cpu);
2114 hrt_server = &cpu_entry->hrt_server;
2115
2116 slack_timer_cancel(hrt_server);
2117
2118 if (likely(bheap_node_in_heap(cpu_entry->hn)))
2119 bheap_delete(server_order, &cpu_heap, cpu_entry->hn);
2120 }
2121
2122 local_irq_restore(flags);
2123
2124 return 0;
2125}
2126
2127static void edf_hsb_task_block(struct task_struct *task)
2128{
2129 unsigned long flags;
2130 cpu_entry_t *entry = task_sched_entry(task);
2131 struct task_struct *linked;
2132 server_t *linked_server;
2133
2134 TRACE_TASK(task, "block at %llu\n", litmus_clock());
2135 set_rt_flags(task, RT_F_BLOCK);
2136
2137 raw_spin_lock_irqsave(global_lock, flags);
2138
2139 linked = entry->linked;
2140 linked_server = entry->linked_server;
2141
2142 unlink(task);
2143
2144 /* TODO: necessary? */
2145 if (task == linked) {
2146 check_donate_slack(linked_server, task);
2147 }
2148
2149 raw_spin_unlock_irqrestore(global_lock, flags);
2150}
2151
2152/*
2153 * A task leaves the system.
2154 */
2155static void edf_hsb_task_exit(struct task_struct *task)
2156{
2157 unsigned long flags;
2158 cpu_entry_t *entry = task_sched_entry(task);
2159
2160 BUG_ON(!is_realtime(task));
2161 TRACE_TASK(task, "RIP at %llu on P%d\n",
2162 TIME(litmus_clock()), tsk_rt(task)->scheduled_on);
2163
2164 raw_spin_lock_irqsave(global_lock, flags);
2165
2166 unlink(task);
2167 if (tsk_rt(task)->scheduled_on != NO_CPU) {
2168 entry->scheduled = NULL;
2169 tsk_rt(task)->scheduled_on = NO_CPU;
2170 }
2171 if (is_srt(task)) {
2172 server_slack_destroy(task_srt_server(task));
2173 server_destroy(task_srt_server(task));
2174 server_free(task_srt_server(task));
2175 task_data_free(tsk_rt(task)->plugin_data);
2176 }
2177
2178 raw_spin_unlock_irqrestore(global_lock, flags);
2179}
2180
2181/*
2182 * Attempts to determine the current scheduler state, then selects the
2183 * next task and updates the scheduler state.
2184 */
2185static struct task_struct* edf_hsb_schedule(struct task_struct *prev)
2186{
2187 unsigned long flags;
2188 int blocks, preempted, sleep, was_slack, np, hrt_preempt, donated;
2189 struct task_struct *curr;
2190 cpu_entry_t *entry = local_cpu_entry;
2191
2192#ifdef CONFIG_RELEASE_MASTER
2193 /* Bail out early if we are the release master.
2194 * The release master never schedules any real-time tasks.
2195 */
2196 if (edf_hsb_release_master == entry->cpu) {
2197 sched_state_task_picked();
2198 return NULL;
2199 }
2200#endif
2201
2202 raw_spin_lock_irqsave(global_lock, flags);
2203
2204 curr = entry->scheduled;
2205
2206 TRACE("server_budget: %llu, server_deadline: %llu, "
2207 "curr_time: %llu, no_slack: %d, ready: %d\n",
2208 TIME(entry->hrt_server.server.budget),
2209 TIME(entry->hrt_server.server.deadline),
2210 TIME(litmus_clock()), entry->hrt_server.no_slack,
2211 entry->hrt_server.ready);
2212
2213 /* Determine state */
2214 blocks = curr && !is_running(curr);
2215 preempted = entry->scheduled != entry->linked;
2216 sleep = curr && get_rt_flags(curr) == RT_F_SLEEP;
2217 was_slack = !list_empty(&slack_queue);
2218 np = curr && is_np(curr);
2219
2220 TRACE("blocks: %d, preempted: %d, sleep: %d, np: %d\n",
2221 blocks, preempted, sleep, np);
2222 if (blocks)
2223 unlink(entry->scheduled);
2224
2225 /* If the task has gone to sleep or exhausted its budget, it
2226 * must complete its current job.
2227 */
2228 if (sleep && !blocks && !preempted)
2229 job_completion(entry, entry->scheduled);
2230
2231 /* Pick the next task if there isn't one currently */
2232 if (!entry->linked)
2233 edf_hsb_pick_next(entry);
2234
2235 /* Set task states */
2236 if (entry->linked != entry->scheduled) {
2237 if (entry->linked)
2238 entry->linked->rt_param.scheduled_on = entry->cpu;
2239 if (entry->scheduled)
2240 entry->scheduled->rt_param.scheduled_on = NO_CPU;
2241 }
2242
2243 entry->scheduled = entry->linked;
2244 entry->scheduled_server = entry->linked_server;
2245 sched_state_task_picked();
2246
2247 /* An non-HRT was preempted by an HRT task. Because of the way linking
2248 * works, it cannot link itself to anything else until the non-migratory
2249 * HRT task is scheduled.
2250 */
2251 hrt_preempt = preempted && entry->linked && curr &&
2252 is_hrt(entry->linked) && !is_hrt(curr);
2253 /* A server just donated slack */
2254 donated = entry->linked && entry->linked_server->type != S_SLACK &&
2255 head_in_list(&server_slack(entry->linked_server)->list);
2256
2257 if (hrt_preempt || donated)
2258 check_for_global_preempt();
2259
2260 if (entry->scheduled)
2261 TRACE_TASK(entry->scheduled, "scheduled at %llu\n",
2262 TIME(litmus_clock()));
2263 else
2264 TRACE("NULL scheduled at %llu\n", TIME(litmus_clock()));
2265
2266 raw_spin_unlock_irqrestore(global_lock, flags);
2267
2268 return entry->scheduled;
2269}
2270
2271/*
2272 * Prepare a task for running in RT mode
2273 */
2274static void edf_hsb_task_new(struct task_struct *task, int on_rq, int running)
2275{
2276 unsigned long flags;
2277 task_data_t *data;
2278 server_t *srt_server = NULL;
2279 cpu_entry_t *entry = task_sched_entry(task);
2280
2281 TRACE_TASK(task, "edf_hsb: task new at %llu\n", TIME(litmus_clock()));
2282
2283 raw_spin_lock_irqsave(global_lock, flags);
2284
2285 /* Setup job parameters */
2286 release_at(task, litmus_clock());
2287
2288 /* Create SRT server */
2289 if (is_srt(task)) {
2290 /* Create SRT server */
2291 srt_server = server_alloc(GFP_ATOMIC);
2292 server_init(srt_server, &server_domain,
2293 task->pid, get_exec_cost(task),
2294 get_rt_period(task), 0);
2295 srt_server->type = S_SRT;
2296
2297 server_slack_create(srt_server);
2298
2299 }
2300
2301 /* Create task plugin data */
2302 data = task_data_alloc(GFP_ATOMIC);
2303 data->owner = task;
2304 data->srt_server = srt_server;
2305 INIT_LIST_HEAD(&data->candidate_list);
2306 tsk_rt(task)->plugin_data = data;
2307
2308 /* Already running, update the cpu entry.
2309 * This tends to happen when the first tasks enter the system.
2310 */
2311 if (running) {
2312 //BUG_ON(entry->scheduled);
2313
2314#ifdef CONFIG_RELEASE_MASTER
2315 if (entry->cpu != edf_hsb_release_master) {
2316#endif
2317 entry->scheduled = task;
2318 tsk_rt(task)->scheduled_on = task_cpu(task);
2319#ifdef CONFIG_RELEASE_MASTER
2320 } else {
2321 /* do not schedule on release master */
2322 /* Cannot preempt! Causing a preemption with a BE task
2323 * somehow leads to that task never blocking during
2324 * a synchronous release. This is a bug!
2325 */
2326 if (!is_be(task))
2327 preempt_if_preemptable(entry->scheduled, entry->cpu);
2328 tsk_rt(task)->scheduled_on = NO_CPU;
2329 }
2330#endif
2331 } else {
2332 task->rt_param.scheduled_on = NO_CPU;
2333 }
2334
2335 task->rt_param.linked_on = NO_CPU;
2336 job_arrival(task, entry);
2337
2338 raw_spin_unlock_irqrestore(global_lock, flags);
2339}
2340
2341static void edf_hsb_task_wake_up(struct task_struct *task)
2342{
2343 lt_t now;
2344 unsigned long flags;
2345 cpu_entry_t *entry = task_sched_entry(task);
2346
2347
2348 TRACE_TASK(task, "wake_up at %llu on %d, %d\n", TIME(litmus_clock()),
2349 task_cpu(task), task->rt_param.task_params.cpu);
2350
2351 raw_spin_lock_irqsave(global_lock, flags);
2352
2353 if (!is_be(task)) {
2354 if (is_srt(task)) {
2355 catchup_srt_server(task);
2356 }
2357
2358 /* Non-BE tasks are not sporadic in this model */
2359 set_rt_flags(task, RT_F_RUNNING);
2360 /* The job blocked while it was being run by a slack server */
2361 if (is_queued(task)) {
2362 check_slack_candidate(task);
2363 goto out;
2364 }
2365 } else {
2366 /* Re-release all BE tasks on wake-up */
2367 now = litmus_clock();
2368
2369 if (is_tardy(task, now)) {
2370 release_at(task, now);
2371 sched_trace_task_release(task);
2372 }
2373 }
2374
2375 job_arrival(task, entry);
2376
2377 out:
2378 raw_spin_unlock_irqrestore(global_lock, flags);
2379}
2380
2381/*
2382 * Unused.
2383 */
2384static void edf_hsb_tick(struct task_struct *t)
2385{
2386}
2387
2388
2389/******************************************************************************
2390 * Plugin
2391 ******************************************************************************/
2392
2393static struct sched_plugin edf_hsb_plugin __cacheline_aligned_in_smp = {
2394 .plugin_name = "EDF-HSB-NOSLACK",
2395
2396 .activate_plugin = edf_hsb_activate_plugin,
2397 .deactivate_plugin = edf_hsb_deactivate_plugin,
2398
2399 .schedule = edf_hsb_schedule,
2400 .admit_task = edf_hsb_admit_task,
2401 .task_block = edf_hsb_task_block,
2402 .task_exit = edf_hsb_task_exit,
2403 .task_new = edf_hsb_task_new,
2404 .task_wake_up = edf_hsb_task_wake_up,
2405 .tick = edf_hsb_tick,
2406
2407 /* From jobs.h */
2408 .complete_job = complete_job,
2409 .release_at = release_at,
2410};
2411
2412static int __init init_edf_hsb(void)
2413{
2414 cpu_entry_t *entry;
2415 hrt_server_t *hrt_server;
2416 server_t *idle_slack;
2417 int rv, cpu;
2418
2419 rv = register_sched_plugin(&edf_hsb_plugin);
2420 if (rv) {
2421 printk(KERN_ERR "Could not register plugin %s.\n",
2422 edf_hsb_plugin.plugin_name);
2423 goto out;
2424 }
2425
2426 rv = make_plugin_proc_dir(&edf_hsb_plugin, &edf_hsb_proc_dir);
2427 if (rv) {
2428 printk(KERN_ERR "Could not create %s procfs dir.\n",
2429 edf_hsb_plugin.plugin_name);
2430 goto out;
2431 }
2432
2433
2434 task_data_cache = KMEM_CACHE(task_data, SLAB_PANIC);
2435
2436 /* Global domains */
2437 edf_domain_init(&srt_domain, NULL, release_srt_jobs);
2438 rt_domain_init(&be_domain, be_ready_order,
2439 NULL, release_be_jobs);
2440 server_domain_init(&server_domain, servers_released,
2441 server_completed, NO_CPU, global_lock);
2442
2443 /* Server proc interfaces */
2444 server_proc_init(&server_domain,
2445 edf_hsb_proc_dir, BE_PROC_NAME,
2446 admit_be_server, list_be_servers,
2447 stop_be_servers);
2448 server_proc_init(&server_domain,
2449 edf_hsb_proc_dir, HRT_PROC_NAME,
2450 admit_hrt_server, list_hrt_servers,
2451 stop_hrt_servers);
2452
2453
2454 /* Global collections */
2455 bheap_init(&cpu_heap);
2456 bheap_init(&be_ready_servers);
2457 INIT_LIST_HEAD(&be_servers);
2458 INIT_LIST_HEAD(&slack_queue);
2459 INIT_LIST_HEAD(&slack_candidates);
2460
2461 for_each_online_cpu(cpu) {
2462 entry = &per_cpu(noslack_cpu_entries, cpu);
2463 hrt_server = &entry->hrt_server;
2464
2465 idle_slack = server_alloc(GFP_ATOMIC);
2466 server_init(idle_slack, &server_domain,
2467 IDLE_SLACK_BASE + cpu,
2468 LLONG_MAX, LLONG_MAX, 1);
2469 idle_slack->deadline = LLONG_MAX;
2470 idle_slack->budget = LLONG_MAX;
2471 idle_slack->job_no = 1;
2472 idle_slack->release = 1;
2473 idle_slack->type = S_SLACK;
2474 add_slack(idle_slack);
2475
2476 entry->cpu = cpu;
2477 entry->linked = NULL;
2478 entry->scheduled = NULL;
2479 entry->linked_server = NULL;
2480
2481 /* HRT server */
2482 hrt_server->server.id = cpu;
2483 hrt_server->server.deadline = 0;
2484 hrt_server->server.period = 0;
2485 hrt_server->server.wcet = 0;
2486 hrt_server->ready = 0;
2487
2488 hrtimer_start_on_info_init(&hrt_server->slack_timer_info);
2489
2490 /* CPU entry bheap nodes */
2491 entry->hn = &cpu_heap_node[cpu];
2492 bheap_node_init(&entry->hn, entry);
2493 }
2494
2495 out:
2496 return rv;
2497}
2498
2499static void exit_edf_hsb(void)
2500{
2501 int cpu;
2502 cpu_entry_t *entry;
2503
2504 stop_be_servers();
2505 stop_hrt_servers();
2506
2507 server_domain_destroy(&server_domain);
2508
2509 for_each_online_cpu(cpu) {
2510 entry = &per_cpu(noslack_cpu_entries, cpu);
2511 server_slack_destroy(&entry->hrt_server.server);
2512 server_destroy(&entry->hrt_server.server);
2513 }
2514
2515 if (edf_hsb_proc_dir) {
2516 remove_plugin_proc_dir(&edf_hsb_plugin);
2517 /* TODO: is this wrong? */
2518 edf_hsb_proc_dir = NULL;
2519 }
2520}
2521
2522module_init(init_edf_hsb);
2523module_exit(exit_edf_hsb);
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-21 09:32:24 -0500