/*
* litmus/sched_cfifo.c
*
* Implementation of the C-FIFO scheduling algorithm.
*
* This implementation is based on G-EDF:
* - CPUs are clustered around L2 or L3 caches.
* - Clusters topology is automatically detected (this is arch dependent
* and is working only on x86 at the moment --- and only with modern
* cpus that exports cpuid4 information)
* - The plugins _does not_ attempt to put tasks in the right cluster i.e.
* the programmer needs to be aware of the topology to place tasks
* in the desired cluster
* - default clustering is around L2 cache (cache index = 2)
* supported clusters are: L1 (private cache: pedf), L2, L3, ALL (all
* online_cpus are placed in a single cluster).
*
* For details on functions, take a look at sched_gsn_edf.c
*
* Currently, we do not support changes in the number of online cpus.
* If the num_online_cpus() dynamically changes, the plugin is broken.
*
* This version uses the simple approach and serializes all scheduling
* decisions by the use of a queue lock. This is probably not the
* best way to do it, but it should suffice for now.
*/
#include <linux/spinlock.h>
#include <linux/percpu.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <litmus/litmus.h>
#include <litmus/jobs.h>
#include <litmus/preempt.h>
#include <litmus/sched_plugin.h>
#include <litmus/fifo_common.h>
#include <litmus/sched_trace.h>
#include <litmus/clustered.h>
#include <litmus/bheap.h>
/* to configure the cluster size */
#include <litmus/litmus_proc.h>
#ifdef CONFIG_SCHED_CPU_AFFINITY
#include <litmus/affinity.h>
#endif
#ifdef CONFIG_LITMUS_SOFTIRQD
#include <litmus/litmus_softirq.h>
#endif
#ifdef CONFIG_LITMUS_PAI_SOFTIRQD
#include <linux/interrupt.h>
#endif
#ifdef CONFIG_LITMUS_NVIDIA
#include <litmus/nvidia_info.h>
#endif
/* Reference configuration variable. Determines which cache level is used to
* group CPUs into clusters. GLOBAL_CLUSTER, which is the default, means that
* all CPUs form a single cluster (just like GSN-EDF).
*/
static enum cache_level cluster_config = GLOBAL_CLUSTER;
struct clusterdomain;
/* cpu_entry_t - maintain the linked and scheduled state
*
* A cpu also contains a pointer to the cfifo_domain_t cluster
* that owns it (struct clusterdomain*)
*/
typedef struct {
int cpu;
struct clusterdomain* cluster; /* owning cluster */
struct task_struct* linked; /* only RT tasks */
struct task_struct* scheduled; /* only RT tasks */
atomic_t will_schedule; /* prevent unneeded IPIs */
struct bheap_node* hn;
} cpu_entry_t;
/* one cpu_entry_t per CPU */
DEFINE_PER_CPU(cpu_entry_t, cfifo_cpu_entries);
#define set_will_schedule() \
(atomic_set(&__get_cpu_var(cfifo_cpu_entries).will_schedule, 1))
#define clear_will_schedule() \
(atomic_set(&__get_cpu_var(cfifo_cpu_entries).will_schedule, 0))
#define test_will_schedule(cpu) \
(atomic_read(&per_cpu(cfifo_cpu_entries, cpu).will_schedule))
#ifdef CONFIG_LITMUS_PAI_SOFTIRQD
struct tasklet_head
{
struct tasklet_struct *head;
struct tasklet_struct **tail;
};
#endif
/*
* In C-FIFO there is a cfifo domain _per_ cluster
* The number of clusters is dynamically determined accordingly to the
* total cpu number and the cluster size
*/
typedef struct clusterdomain {
/* rt_domain for this cluster */
rt_domain_t domain;
/* cpus in this cluster */
cpu_entry_t* *cpus;
/* map of this cluster cpus */
cpumask_var_t cpu_map;
/* the cpus queue themselves according to priority in here */
struct bheap_node *heap_node;
struct bheap cpu_heap;
/* lock for this cluster */
#define cfifo_lock domain.ready_lock
#ifdef CONFIG_LITMUS_PAI_SOFTIRQD
struct tasklet_head pending_tasklets;
#endif
} cfifo_domain_t;
/* a cfifo_domain per cluster; allocation is done at init/activation time */
cfifo_domain_t *cfifo;
#define remote_cluster(cpu) ((cfifo_domain_t *) per_cpu(cfifo_cpu_entries, cpu).cluster)
#define task_cpu_cluster(task) remote_cluster(get_partition(task))
/* Uncomment WANT_ALL_SCHED_EVENTS if you want to see all scheduling
* decisions in the TRACE() log; uncomment VERBOSE_INIT for verbose
* information during the initialization of the plugin (e.g., topology)
#define WANT_ALL_SCHED_EVENTS
*/
#define VERBOSE_INIT
static int cpu_lower_prio(struct bheap_node *_a, struct bheap_node *_b)
{
cpu_entry_t *a, *b;
a = _a->value;
b = _b->value;
/* Note that a and b are inverted: we want the lowest-priority CPU at
* the top of the heap.
*/
return fifo_higher_prio(b->linked, a->linked);
}
/* update_cpu_position - Move the cpu entry to the correct place to maintain
* order in the cpu queue. Caller must hold cfifo lock.
*/
static void update_cpu_position(cpu_entry_t *entry)
{
cfifo_domain_t *cluster = entry->cluster;
if (likely(bheap_node_in_heap(entry->hn)))
bheap_delete(cpu_lower_prio,
&cluster->cpu_heap,
entry->hn);
bheap_insert(cpu_lower_prio, &cluster->cpu_heap, entry->hn);
}
/* caller must hold cfifo lock */
static cpu_entry_t* lowest_prio_cpu(cfifo_domain_t *cluster)
{
struct bheap_node* hn;
hn = bheap_peek(cpu_lower_prio, &cluster->cpu_heap);
return hn->value;
}
/* link_task_to_cpu - Update the link of a CPU.
* Handles the case where the to-be-linked task is already
* scheduled on a different CPU.
*/
static noinline void link_task_to_cpu(struct task_struct* linked,
cpu_entry_t *entry)
{
cpu_entry_t *sched;
struct task_struct* tmp;
int on_cpu;
BUG_ON(linked && !is_realtime(linked));
/* Currently linked task is set to be unlinked. */
if (entry->linked) {
entry->linked->rt_param.linked_on = NO_CPU;
}
/* Link new task to CPU. */
if (linked) {
set_rt_flags(linked, RT_F_RUNNING);
/* handle task is already scheduled somewhere! */
on_cpu = linked->rt_param.scheduled_on;
if (on_cpu != NO_CPU) {
sched = &per_cpu(cfifo_cpu_entries, on_cpu);
/* this should only happen if not linked already */
BUG_ON(sched->linked == linked);
/* If we are already scheduled on the CPU to which we
* wanted to link, we don't need to do the swap --
* we just link ourselves to the CPU and depend on
* the caller to get things right.
*/
if (entry != sched) {
TRACE_TASK(linked,
"already scheduled on %d, updating link.\n",
sched->cpu);
tmp = sched->linked;
linked->rt_param.linked_on = sched->cpu;
sched->linked = linked;
update_cpu_position(sched);
linked = tmp;
}
}
if (linked) /* might be NULL due to swap */
linked->rt_param.linked_on = entry->cpu;
}
entry->linked = linked;
#ifdef WANT_ALL_SCHED_EVENTS
if (linked)
TRACE_TASK(linked, "linked to %d.\n", entry->cpu);
else
TRACE("NULL linked to %d.\n", entry->cpu);
#endif
update_cpu_position(entry);
}
/* unlink - Make sure a task is not linked any longer to an entry
* where it was linked before. Must hold cfifo_lock.
*/
static noinline void unlink(struct task_struct* t)
{
cpu_entry_t *entry;
if (t->rt_param.linked_on != NO_CPU) {
/* unlink */
entry = &per_cpu(cfifo_cpu_entries, t->rt_param.linked_on);
t->rt_param.linked_on = NO_CPU;
link_task_to_cpu(NULL, entry);
} else if (is_queued(t)) {
/* This is an interesting situation: t is scheduled,
* but was just recently unlinked. It cannot be
* linked anywhere else (because then it would have
* been relinked to this CPU), thus it must be in some
* queue. We must remove it from the list in this
* case.
*
* in C-FIFO case is should be somewhere in the queue for
* its domain, therefore and we can get the domain using
* task_cpu_cluster
*/
remove(&(task_cpu_cluster(t))->domain, t);
}
}
/* preempt - force a CPU to reschedule
*/
static void preempt(cpu_entry_t *entry)
{
preempt_if_preemptable(entry->scheduled, entry->cpu);
}
/* requeue - Put an unlinked task into c-fifo domain.
* Caller must hold cfifo_lock.
*/
static noinline void requeue(struct task_struct* task)
{
cfifo_domain_t *cluster = task_cpu_cluster(task);
BUG_ON(!task);
/* sanity check before insertion */
BUG_ON(is_queued(task));
if (is_released(task, litmus_clock()))
__add_ready(&cluster->domain, task);
else {
/* it has got to wait */
add_release(&cluster->domain, task);
}
}
#ifdef CONFIG_SCHED_CPU_AFFINITY
static cpu_entry_t* cfifo_get_nearest_available_cpu(
cfifo_domain_t *cluster, cpu_entry_t* start)
{
cpu_entry_t* affinity;
get_nearest_available_cpu(affinity, start, cfifo_cpu_entries, -1);
/* make sure CPU is in our cluster */
if(affinity && cpu_isset(affinity->cpu, *cluster->cpu_map))
return(affinity);
else
return(NULL);
}
#endif
/* check for any necessary preemptions */
static void check_for_preemptions(cfifo_domain_t *cluster)
{
struct task_struct *task;
cpu_entry_t *last;
for(last = lowest_prio_cpu(cluster);
fifo_preemption_needed(&cluster->domain, last->linked);
last = lowest_prio_cpu(cluster)) {
/* preemption necessary */
task = __take_ready(&cluster->domain);
#ifdef CONFIG_SCHED_CPU_AFFINITY
{
cpu_entry_t* affinity =
cfifo_get_nearest_available_cpu(cluster,
&per_cpu(cfifo_cpu_entries, task_cpu(task)));
if(affinity)
last = affinity;
else if(last->linked)
requeue(last->linked);
}
#else
if (last->linked)
requeue(last->linked);
#endif
TRACE("check_for_preemptions: attempting to link task %d to %d\n",
task->pid, last->cpu);
link_task_to_cpu(task, last);
preempt(last);
}
}
/* cfifo_job_arrival: task is either resumed or released */
static noinline void cfifo_job_arrival(struct task_struct* task)
{
cfifo_domain_t *cluster = task_cpu_cluster(task);
BUG_ON(!task);
requeue(task);
check_for_preemptions(cluster);
}
static void cfifo_release_jobs(rt_domain_t* rt, struct bheap* tasks)
{
cfifo_domain_t* cluster = container_of(rt, cfifo_domain_t, domain);
unsigned long flags;
raw_spin_lock_irqsave(&cluster->cfifo_lock, flags);
__merge_ready(&cluster->domain, tasks);
check_for_preemptions(cluster);
raw_spin_unlock_irqrestore(&cluster->cfifo_lock, flags);
}
/* caller holds cfifo_lock */
static noinline void job_completion(struct task_struct *t, int forced)
{
BUG_ON(!t);
sched_trace_task_completion(t, forced);
#ifdef CONFIG_LITMUS_NVIDIA
atomic_set(&tsk_rt(t)->nv_int_count, 0);
#endif
TRACE_TASK(t, "job_completion().\n");
/* set flags */
set_rt_flags(t, RT_F_SLEEP);
/* prepare for next period */
prepare_for_next_period(t);
if (is_released(t, litmus_clock()))
sched_trace_task_release(t);
/* unlink */
unlink(t);
/* requeue
* But don't requeue a blocking task. */
if (is_running(t))
cfifo_job_arrival(t);
}
/* cfifo_tick - this function is called for every local timer
* interrupt.
*
* checks whether the current task has expired and checks
* whether we need to preempt it if it has not expired
*/
static void cfifo_tick(struct task_struct* t)
{
if (is_realtime(t) && budget_enforced(t) && budget_exhausted(t)) {
if (!is_np(t)) {
/* np tasks will be preempted when they become
* preemptable again
*/
litmus_reschedule_local();
set_will_schedule();
TRACE("cfifo_scheduler_tick: "
"%d is preemptable "
" => FORCE_RESCHED\n", t->pid);
} else if (is_user_np(t)) {
TRACE("cfifo_scheduler_tick: "
"%d is non-preemptable, "
"preemption delayed.\n", t->pid);
request_exit_np(t);
}
}
}
#ifdef CONFIG_LITMUS_PAI_SOFTIRQD
static void __do_lit_tasklet(struct tasklet_struct* tasklet, unsigned long flushed)
{
if (!atomic_read(&tasklet->count)) {
sched_trace_tasklet_begin(tasklet->owner);
if (!test_and_clear_bit(TASKLET_STATE_SCHED, &tasklet->state))
{
BUG();
}
TRACE("%s: Invoking tasklet with owner pid = %d (flushed = %d).\n", __FUNCTION__, tasklet->owner->pid, flushed);
tasklet->func(tasklet->data);
tasklet_unlock(tasklet);
sched_trace_tasklet_end(tasklet->owner, flushed);
}
else {
BUG();
}
}
static void __extract_tasklets(cfifo_domain_t* cluster, struct task_struct* task, struct tasklet_head* task_tasklets)
{
struct tasklet_struct* step;
struct tasklet_struct* tasklet;
struct tasklet_struct* prev;
task_tasklets->head = NULL;
task_tasklets->tail = &(task_tasklets->head);
prev = NULL;
for(step = cluster->pending_tasklets.head; step != NULL; step = step->next)
{
if(step->owner == task)
{
TRACE("%s: Found tasklet to flush: %d\n", __FUNCTION__, step->owner->pid);
tasklet = step;
if(prev) {
prev->next = tasklet->next;
}
else if(cluster->pending_tasklets.head == tasklet) {
// we're at the head.
cluster->pending_tasklets.head = tasklet->next;
}
if(cluster->pending_tasklets.tail == &tasklet) {
// we're at the tail
if(prev) {
cluster->pending_tasklets.tail = &prev;
}
else {
cluster->pending_tasklets.tail = &(cluster->pending_tasklets.head);
}
}
tasklet->next = NULL;
*(task_tasklets->tail) = tasklet;
task_tasklets->tail = &(tasklet->next);
}
else {
prev = step;
}
}
}
static void flush_tasklets(cfifo_domain_t* cluster, struct task_struct* task)
{
unsigned long flags;
struct tasklet_head task_tasklets;
struct tasklet_struct* step;
raw_spin_lock_irqsave(&cluster->cfifo_lock, flags);
__extract_tasklets(cluster, task, &task_tasklets);
raw_spin_unlock_irqrestore(&cluster->cfifo_lock, flags);
if(cluster->pending_tasklets.head != NULL) {
TRACE("%s: Flushing tasklets for %d...\n", __FUNCTION__, task->pid);
}
// now execute any flushed tasklets.
for(step = cluster->pending_tasklets.head; step != NULL; /**/)
{
struct tasklet_struct* temp = step->next;
step->next = NULL;
__do_lit_tasklet(step, 1ul);
step = temp;
}
}
static void do_lit_tasklets(cfifo_domain_t* cluster, struct task_struct* sched_task)
{
int work_to_do = 1;
struct tasklet_struct *tasklet = NULL;
//struct tasklet_struct *step;
unsigned long flags;
while(work_to_do) {
// remove tasklet at head of list if it has higher priority.
raw_spin_lock_irqsave(&cluster->cfifo_lock, flags);
/*
step = cluster->pending_tasklets.head;
TRACE("%s: (BEFORE) dumping tasklet queue...\n", __FUNCTION__);
while(step != NULL){
TRACE("%s: %p (%d)\n", __FUNCTION__, step, step->owner->pid);
step = step->next;
}
TRACE("%s: tail = %p (%d)\n", __FUNCTION__, *(cluster->pending_tasklets.tail), (*(cluster->pending_tasklets.tail) != NULL) ? (*(cluster->pending_tasklets.tail))->owner->pid : -1);
TRACE("%s: done.\n", __FUNCTION__);
*/
if(cluster->pending_tasklets.head != NULL) {
// remove tasklet at head.
tasklet = cluster->pending_tasklets.head;
if(fifo_higher_prio(tasklet->owner, sched_task)) {
if(NULL == tasklet->next) {
// tasklet is at the head, list only has one element
TRACE("%s: Tasklet for %d is the last element in tasklet queue.\n", __FUNCTION__, tasklet->owner->pid);
cluster->pending_tasklets.tail = &(cluster->pending_tasklets.head);
}
// remove the tasklet from the queue
cluster->pending_tasklets.head = tasklet->next;
TRACE("%s: Removed tasklet for %d from tasklet queue.\n", __FUNCTION__, tasklet->owner->pid);
}
else {
TRACE("%s: Pending tasklet (%d) does not have priority to run on this CPU (%d).\n", __FUNCTION__, tasklet->owner->pid, smp_processor_id());
tasklet = NULL;
}
}
else {
TRACE("%s: Tasklet queue is empty.\n", __FUNCTION__);
}
/*
step = cluster->pending_tasklets.head;
TRACE("%s: (AFTER) dumping tasklet queue...\n", __FUNCTION__);
while(step != NULL){
TRACE("%s: %p (%d)\n", __FUNCTION__, step, step->owner->pid);
step = step->next;
}
TRACE("%s: tail = %p (%d)\n", __FUNCTION__, *(cluster->pending_tasklets.tail), (*(cluster->pending_tasklets.tail) != NULL) ? (*(cluster->pending_tasklets.tail))->owner->pid : -1);
TRACE("%s: done.\n", __FUNCTION__);
*/
raw_spin_unlock_irqrestore(&cluster->cfifo_lock, flags);
if(tasklet) {
__do_lit_tasklet(tasklet, 0ul);
tasklet = NULL;
}
else {
work_to_do = 0;
}
}
//TRACE("%s: exited.\n", __FUNCTION__);
}
static void run_tasklets(struct task_struct* sched_task)
{
cfifo_domain_t* cluster;
#if 0
int task_is_rt = is_realtime(sched_task);
cfifo_domain_t* cluster;
if(is_realtime(sched_task)) {
cluster = task_cpu_cluster(sched_task);
}
else {
cluster = remote_cluster(get_cpu());
}
if(cluster && cluster->pending_tasklets.head != NULL) {
TRACE("%s: There are tasklets to process.\n", __FUNCTION__);
do_lit_tasklets(cluster, sched_task);
}
if(!task_is_rt) {
put_cpu_no_resched();
}
#else
preempt_disable();
cluster = (is_realtime(sched_task)) ?
task_cpu_cluster(sched_task) :
remote_cluster(smp_processor_id());
if(cluster && cluster->pending_tasklets.head != NULL) {
TRACE("%s: There are tasklets to process.\n", __FUNCTION__);
do_lit_tasklets(cluster, sched_task);
}
preempt_enable_no_resched();
#endif
}
static void __add_pai_tasklet(struct tasklet_struct* tasklet, cfifo_domain_t* cluster)
{
struct tasklet_struct* step;
/*
step = cluster->pending_tasklets.head;
TRACE("%s: (BEFORE) dumping tasklet queue...\n", __FUNCTION__);
while(step != NULL){
TRACE("%s: %p (%d)\n", __FUNCTION__, step, step->owner->pid);
step = step->next;
}
TRACE("%s: tail = %p (%d)\n", __FUNCTION__, *(cluster->pending_tasklets.tail), (*(cluster->pending_tasklets.tail) != NULL) ? (*(cluster->pending_tasklets.tail))->owner->pid : -1);
TRACE("%s: done.\n", __FUNCTION__);
*/
tasklet->next = NULL; // make sure there are no old values floating around
step = cluster->pending_tasklets.head;
if(step == NULL) {
TRACE("%s: tasklet queue empty. inserting tasklet for %d at head.\n", __FUNCTION__, tasklet->owner->pid);
// insert at tail.
*(cluster->pending_tasklets.tail) = tasklet;
cluster->pending_tasklets.tail = &(tasklet->next);
}
else if((*(cluster->pending_tasklets.tail) != NULL) &&
fifo_higher_prio((*(cluster->pending_tasklets.tail))->owner, tasklet->owner)) {
// insert at tail.
TRACE("%s: tasklet belongs at end. inserting tasklet for %d at tail.\n", __FUNCTION__, tasklet->owner->pid);
*(cluster->pending_tasklets.tail) = tasklet;
cluster->pending_tasklets.tail = &(tasklet->next);
}
else {
//WARN_ON(1 == 1);
// insert the tasklet somewhere in the middle.
TRACE("%s: tasklet belongs somewhere in the middle.\n", __FUNCTION__);
while(step->next && fifo_higher_prio(step->next->owner, tasklet->owner)) {
step = step->next;
}
// insert tasklet right before step->next.
TRACE("%s: inserting tasklet for %d between %d and %d.\n", __FUNCTION__, tasklet->owner->pid, step->owner->pid, (step->next) ? step->next->owner->pid : -1);
tasklet->next = step->next;
step->next = tasklet;
// patch up the head if needed.
if(cluster->pending_tasklets.head == step)
{
TRACE("%s: %d is the new tasklet queue head.\n", __FUNCTION__, tasklet->owner->pid);
cluster->pending_tasklets.head = tasklet;
}
}
/*
step = cluster->pending_tasklets.head;
TRACE("%s: (AFTER) dumping tasklet queue...\n", __FUNCTION__);
while(step != NULL){
TRACE("%s: %p (%d)\n", __FUNCTION__, step, step->owner->pid);
step = step->next;
}
TRACE("%s: tail = %p (%d)\n", __FUNCTION__, *(cluster->pending_tasklets.tail), (*(cluster->pending_tasklets.tail) != NULL) ? (*(cluster->pending_tasklets.tail))->owner->pid : -1);
TRACE("%s: done.\n", __FUNCTION__);
*/
// TODO: Maintain this list in priority order.
// tasklet->next = NULL;
// *(cluster->pending_tasklets.tail) = tasklet;
// cluster->pending_tasklets.tail = &tasklet->next;
}
static int enqueue_pai_tasklet(struct tasklet_struct* tasklet)
{
cfifo_domain_t *cluster = NULL;
cpu_entry_t *targetCPU = NULL;
int thisCPU;
int runLocal = 0;
int runNow = 0;
unsigned long flags;
if(unlikely((tasklet->owner == NULL) || !is_realtime(tasklet->owner)))
{
TRACE("%s: No owner associated with this tasklet!\n", __FUNCTION__);
return 0;
}
cluster = task_cpu_cluster(tasklet->owner);
raw_spin_lock_irqsave(&cluster->cfifo_lock, flags);
thisCPU = smp_processor_id();
#if 1
#ifdef CONFIG_SCHED_CPU_AFFINITY
{
cpu_entry_t* affinity = NULL;
// use this CPU if it is in our cluster and isn't running any RT work.
if(cpu_isset(thisCPU, *cluster->cpu_map) && (__get_cpu_var(cfifo_cpu_entries).linked == NULL)) {
affinity = &(__get_cpu_var(cfifo_cpu_entries));
}
else {
// this CPU is busy or shouldn't run tasklet in this cluster.
// look for available near by CPUs.
// NOTE: Affinity towards owner and not this CPU. Is this right?
affinity =
cfifo_get_nearest_available_cpu(cluster,
&per_cpu(cfifo_cpu_entries, task_cpu(tasklet->owner)));
}
targetCPU = affinity;
}
#endif
#endif
if (targetCPU == NULL) {
targetCPU = lowest_prio_cpu(cluster);
}
if (fifo_higher_prio(tasklet->owner, targetCPU->linked)) {
if (thisCPU == targetCPU->cpu) {
TRACE("%s: Run tasklet locally (and now).\n", __FUNCTION__);
runLocal = 1;
runNow = 1;
}
else {
TRACE("%s: Run tasklet remotely (and now).\n", __FUNCTION__);
runLocal = 0;
runNow = 1;
}
}
else {
runLocal = 0;
runNow = 0;
}
if(!runLocal) {
// enqueue the tasklet
__add_pai_tasklet(tasklet, cluster);
}
raw_spin_unlock_irqrestore(&cluster->cfifo_lock, flags);
if (runLocal /*&& runNow */) { // runNow == 1 is implied
TRACE("%s: Running tasklet on CPU where it was received.\n", __FUNCTION__);
__do_lit_tasklet(tasklet, 0ul);
}
else if (runNow /*&& !runLocal */) { // runLocal == 0 is implied
TRACE("%s: Triggering CPU %d to run tasklet.\n", __FUNCTION__, targetCPU->cpu);
preempt(targetCPU); // need to be protected by cfifo_lock?
}
else {
TRACE("%s: Scheduling of tasklet was deferred.\n", __FUNCTION__);
}
return(1); // success
}
#endif
/* Getting schedule() right is a bit tricky. schedule() may not make any
* assumptions on the state of the current task since it may be called for a
* number of reasons. The reasons include a scheduler_tick() determined that it
* was necessary, because sys_exit_np() was called, because some Linux
* subsystem determined so, or even (in the worst case) because there is a bug
* hidden somewhere. Thus, we must take extreme care to determine what the
* current state is.
*
* The CPU could currently be scheduling a task (or not), be linked (or not).
*
* The following assertions for the scheduled task could hold:
*
* - !is_running(scheduled) // the job blocks
* - scheduled->timeslice == 0 // the job completed (forcefully)
* - get_rt_flag() == RT_F_SLEEP // the job completed (by syscall)
* - linked != scheduled // we need to reschedule (for any reason)
* - is_np(scheduled) // rescheduling must be delayed,
* sys_exit_np must be requested
*
* Any of these can occur together.
*/
static struct task_struct* cfifo_schedule(struct task_struct * prev)
{
cpu_entry_t* entry = &__get_cpu_var(cfifo_cpu_entries);
cfifo_domain_t *cluster = entry->cluster;
int out_of_time, sleep, preempt, np, exists, blocks;
struct task_struct* next = NULL;
raw_spin_lock(&cluster->cfifo_lock);
clear_will_schedule();
/* sanity checking */
BUG_ON(entry->scheduled && entry->scheduled != prev);
BUG_ON(entry->scheduled && !is_realtime(prev));
BUG_ON(is_realtime(prev) && !entry->scheduled);
/* (0) Determine state */
exists = entry->scheduled != NULL;
blocks = exists && !is_running(entry->scheduled);
out_of_time = exists &&
budget_enforced(entry->scheduled) &&
budget_exhausted(entry->scheduled);
np = exists && is_np(entry->scheduled);
sleep = exists && get_rt_flags(entry->scheduled) == RT_F_SLEEP;
preempt = entry->scheduled != entry->linked;
#ifdef WANT_ALL_SCHED_EVENTS
TRACE_TASK(prev, "invoked cfifo_schedule.\n");
#endif
if (exists)
TRACE_TASK(prev,
"blocks:%d out_of_time:%d np:%d sleep:%d preempt:%d "
"state:%d sig:%d\n",
blocks, out_of_time, np, sleep, preempt,
prev->state, signal_pending(prev));
if (entry->linked && preempt)
TRACE_TASK(prev, "will be preempted by %s/%d\n",
entry->linked->comm, entry->linked->pid);
/* If a task blocks we have no choice but to reschedule.
*/
if (blocks)
unlink(entry->scheduled);
/* Request a sys_exit_np() call if we would like to preempt but cannot.
* We need to make sure to update the link structure anyway in case
* that we are still linked. Multiple calls to request_exit_np() don't
* hurt.
*/
if (np && (out_of_time || preempt || sleep)) {
unlink(entry->scheduled);
request_exit_np(entry->scheduled);
}
/* Any task that is preemptable and either exhausts its execution
* budget or wants to sleep completes. We may have to reschedule after
* this. Don't do a job completion if we block (can't have timers running
* for blocked jobs). Preemption go first for the same reason.
*/
if (!np && (out_of_time || sleep) && !blocks && !preempt)
job_completion(entry->scheduled, !sleep);
/* Link pending task if we became unlinked.
*/
if (!entry->linked)
link_task_to_cpu(__take_ready(&cluster->domain), entry);
/* The final scheduling decision. Do we need to switch for some reason?
* If linked is different from scheduled, then select linked as next.
*/
if ((!np || blocks) &&
entry->linked != entry->scheduled) {
/* Schedule a linked job? */
if (entry->linked) {
entry->linked->rt_param.scheduled_on = entry->cpu;
next = entry->linked;
}
if (entry->scheduled) {
/* not gonna be scheduled soon */
entry->scheduled->rt_param.scheduled_on = NO_CPU;
TRACE_TASK(entry->scheduled, "scheduled_on = NO_CPU\n");
}
} else
/* Only override Linux scheduler if we have a real-time task
* scheduled that needs to continue.
*/
if (exists)
next = prev;
sched_state_task_picked();
raw_spin_unlock(&cluster->cfifo_lock);
#ifdef WANT_ALL_SCHED_EVENTS
TRACE("cfifo_lock released, next=0x%p\n", next);
if (next)
TRACE_TASK(next, "scheduled at %llu\n", litmus_clock());
else if (exists && !next)
TRACE("becomes idle at %llu.\n", litmus_clock());
#endif
return next;
}
/* _finish_switch - we just finished the switch away from prev
*/
static void cfifo_finish_switch(struct task_struct *prev)
{
cpu_entry_t* entry = &__get_cpu_var(cfifo_cpu_entries);
entry->scheduled = is_realtime(current) ? current : NULL;
#ifdef WANT_ALL_SCHED_EVENTS
TRACE_TASK(prev, "switched away from\n");
#endif
}
/* Prepare a task for running in RT mode
*/
static void cfifo_task_new(struct task_struct * t, int on_rq, int running)
{
unsigned long flags;
cpu_entry_t* entry;
cfifo_domain_t* cluster;
TRACE("cfifo: task new %d\n", t->pid);
/* the cluster doesn't change even if t is running */
cluster = task_cpu_cluster(t);
raw_spin_lock_irqsave(&cluster->cfifo_lock, flags);
/* setup job params */
release_at(t, litmus_clock());
if (running) {
entry = &per_cpu(cfifo_cpu_entries, task_cpu(t));
BUG_ON(entry->scheduled);
entry->scheduled = t;
tsk_rt(t)->scheduled_on = task_cpu(t);
} else {
t->rt_param.scheduled_on = NO_CPU;
}
t->rt_param.linked_on = NO_CPU;
cfifo_job_arrival(t);
raw_spin_unlock_irqrestore(&cluster->cfifo_lock, flags);
}
static void cfifo_task_wake_up(struct task_struct *task)
{
unsigned long flags;
//lt_t now;
cfifo_domain_t *cluster;
TRACE_TASK(task, "wake_up at %llu\n", litmus_clock());
cluster = task_cpu_cluster(task);
raw_spin_lock_irqsave(&cluster->cfifo_lock, flags);
#if 0 // sporadic task model
/* We need to take suspensions because of semaphores into
* account! If a job resumes after being suspended due to acquiring
* a semaphore, it should never be treated as a new job release.
*/
if (get_rt_flags(task) == RT_F_EXIT_SEM) {
set_rt_flags(task, RT_F_RUNNING);
} else {
now = litmus_clock();
if (is_tardy(task, now)) {
/* new sporadic release */
release_at(task, now);
sched_trace_task_release(task);
}
else {
if (task->rt.time_slice) {
/* came back in time before deadline
*/
set_rt_flags(task, RT_F_RUNNING);
}
}
}
#endif
//BUG_ON(tsk_rt(task)->linked_on != NO_CPU);
set_rt_flags(task, RT_F_RUNNING); // periodic model
if(tsk_rt(task)->linked_on == NO_CPU)
cfifo_job_arrival(task);
else
TRACE("WTF, mate?!\n");
raw_spin_unlock_irqrestore(&cluster->cfifo_lock, flags);
}
static void cfifo_task_block(struct task_struct *t)
{
unsigned long flags;
cfifo_domain_t *cluster;
TRACE_TASK(t, "block at %llu\n", litmus_clock());
cluster = task_cpu_cluster(t);
/* unlink if necessary */
raw_spin_lock_irqsave(&cluster->cfifo_lock, flags);
unlink(t);
raw_spin_unlock_irqrestore(&cluster->cfifo_lock, flags);
BUG_ON(!is_realtime(t));
}
static void cfifo_task_exit(struct task_struct * t)
{
unsigned long flags;
cfifo_domain_t *cluster = task_cpu_cluster(t);
/* unlink if necessary */
raw_spin_lock_irqsave(&cluster->cfifo_lock, flags);
unlink(t);
if (tsk_rt(t)->scheduled_on != NO_CPU) {
cpu_entry_t *cpu;
cpu = &per_cpu(cfifo_cpu_entries, tsk_rt(t)->scheduled_on);
cpu->scheduled = NULL;
tsk_rt(t)->scheduled_on = NO_CPU;
}
raw_spin_unlock_irqrestore(&cluster->cfifo_lock, flags);
#ifdef CONFIG_LITMUS_PAI_SOFTIRQD
flush_tasklets(cluster, t);
#endif
BUG_ON(!is_realtime(t));
TRACE_TASK(t, "RIP\n");
}
static long cfifo_admit_task(struct task_struct* tsk)
{
return task_cpu(tsk) == tsk->rt_param.task_params.cpu ? 0 : -EINVAL;
}
#ifdef CONFIG_LITMUS_LOCKING
#include <litmus/fdso.h>
static void __set_priority_inheritance(struct task_struct* t, struct task_struct* prio_inh)
{
int linked_on;
int check_preempt = 0;
cfifo_domain_t* cluster = task_cpu_cluster(t);
if(prio_inh != NULL)
TRACE_TASK(t, "inherits priority from %s/%d\n", prio_inh->comm, prio_inh->pid);
else
TRACE_TASK(t, "inherits priority from %p\n", prio_inh);
sched_trace_eff_prio_change(t, prio_inh);
tsk_rt(t)->inh_task = prio_inh;
linked_on = tsk_rt(t)->linked_on;
/* If it is scheduled, then we need to reorder the CPU heap. */
if (linked_on != NO_CPU) {
TRACE_TASK(t, "%s: linked on %d\n",
__FUNCTION__, linked_on);
/* Holder is scheduled; need to re-order CPUs.
* We can't use heap_decrease() here since
* the cpu_heap is ordered in reverse direction, so
* it is actually an increase. */
bheap_delete(cpu_lower_prio, &cluster->cpu_heap,
per_cpu(cfifo_cpu_entries, linked_on).hn);
bheap_insert(cpu_lower_prio, &cluster->cpu_heap,
per_cpu(cfifo_cpu_entries, linked_on).hn);
} else {
/* holder may be queued: first stop queue changes */
raw_spin_lock(&cluster->domain.release_lock);
if (is_queued(t)) {
TRACE_TASK(t, "%s: is queued\n", __FUNCTION__);
/* We need to update the position of holder in some
* heap. Note that this could be a release heap if we
* budget enforcement is used and this job overran. */
check_preempt = !bheap_decrease(fifo_ready_order, tsk_rt(t)->heap_node);
} else {
/* Nothing to do: if it is not queued and not linked
* then it is either sleeping or currently being moved
* by other code (e.g., a timer interrupt handler) that
* will use the correct priority when enqueuing the
* task. */
TRACE_TASK(t, "%s: is NOT queued => Done.\n", __FUNCTION__);
}
raw_spin_unlock(&cluster->domain.release_lock);
/* If holder was enqueued in a release heap, then the following
* preemption check is pointless, but we can't easily detect
* that case. If you want to fix this, then consider that
* simply adding a state flag requires O(n) time to update when
* releasing n tasks, which conflicts with the goal to have
* O(log n) merges. */
if (check_preempt) {
/* heap_decrease() hit the top level of the heap: make
* sure preemption checks get the right task, not the
* potentially stale cache. */
bheap_uncache_min(fifo_ready_order, &cluster->domain.ready_queue);
check_for_preemptions(cluster);
}
}
}
/* called with IRQs off */
static void set_priority_inheritance(struct task_struct* t, struct task_struct* prio_inh)
{
cfifo_domain_t* cluster = task_cpu_cluster(t);
raw_spin_lock(&cluster->cfifo_lock);
__set_priority_inheritance(t, prio_inh);
#ifdef CONFIG_LITMUS_SOFTIRQD
if(tsk_rt(t)->cur_klitirqd != NULL)
{
TRACE_TASK(t, "%s/%d inherits a new priority!\n",
tsk_rt(t)->cur_klitirqd->comm, tsk_rt(t)->cur_klitirqd->pid);
__set_priority_inheritance(tsk_rt(t)->cur_klitirqd, prio_inh);
}
#endif
raw_spin_unlock(&cluster->cfifo_lock);
}
/* called with IRQs off */
static void __clear_priority_inheritance(struct task_struct* t)
{
TRACE_TASK(t, "priority restored\n");
if(tsk_rt(t)->scheduled_on != NO_CPU)
{
sched_trace_eff_prio_change(t, NULL);
tsk_rt(t)->inh_task = NULL;
/* Check if rescheduling is necessary. We can't use heap_decrease()
* since the priority was effectively lowered. */
unlink(t);
cfifo_job_arrival(t);
}
else
{
__set_priority_inheritance(t, NULL);
}
#ifdef CONFIG_LITMUS_SOFTIRQD
if(tsk_rt(t)->cur_klitirqd != NULL)
{
TRACE_TASK(t, "%s/%d inheritance set back to owner.\n",
tsk_rt(t)->cur_klitirqd->comm, tsk_rt(t)->cur_klitirqd->pid);
if(tsk_rt(tsk_rt(t)->cur_klitirqd)->scheduled_on != NO_CPU)
{
sched_trace_eff_prio_change(tsk_rt(t)->cur_klitirqd, t);
tsk_rt(tsk_rt(t)->cur_klitirqd)->inh_task = t;
/* Check if rescheduling is necessary. We can't use heap_decrease()
* since the priority was effectively lowered. */
unlink(tsk_rt(t)->cur_klitirqd);
cfifo_job_arrival(tsk_rt(t)->cur_klitirqd);
}
else
{
__set_priority_inheritance(tsk_rt(t)->cur_klitirqd, t);
}
}
#endif
}
/* called with IRQs off */
static void clear_priority_inheritance(struct task_struct* t)
{
cfifo_domain_t* cluster = task_cpu_cluster(t);
raw_spin_lock(&cluster->cfifo_lock);
__clear_priority_inheritance(t);
raw_spin_unlock(&cluster->cfifo_lock);
}
#ifdef CONFIG_LITMUS_SOFTIRQD
/* called with IRQs off */
static void set_priority_inheritance_klitirqd(struct task_struct* klitirqd,
struct task_struct* old_owner,
struct task_struct* new_owner)
{
cfifo_domain_t* cluster = task_cpu_cluster(klitirqd);
BUG_ON(!(tsk_rt(klitirqd)->is_proxy_thread));
raw_spin_lock(&cluster->cfifo_lock);
if(old_owner != new_owner)
{
if(old_owner)
{
// unreachable?
tsk_rt(old_owner)->cur_klitirqd = NULL;
}
TRACE_TASK(klitirqd, "giving ownership to %s/%d.\n",
new_owner->comm, new_owner->pid);
tsk_rt(new_owner)->cur_klitirqd = klitirqd;
}
__set_priority_inheritance(klitirqd,
(tsk_rt(new_owner)->inh_task == NULL) ?
new_owner :
tsk_rt(new_owner)->inh_task);
raw_spin_unlock(&cluster->cfifo_lock);
}
/* called with IRQs off */
static void clear_priority_inheritance_klitirqd(struct task_struct* klitirqd,
struct task_struct* old_owner)
{
cfifo_domain_t* cluster = task_cpu_cluster(klitirqd);
BUG_ON(!(tsk_rt(klitirqd)->is_proxy_thread));
raw_spin_lock(&cluster->cfifo_lock);
TRACE_TASK(klitirqd, "priority restored\n");
if(tsk_rt(klitirqd)->scheduled_on != NO_CPU)
{
tsk_rt(klitirqd)->inh_task = NULL;
/* Check if rescheduling is necessary. We can't use heap_decrease()
* since the priority was effectively lowered. */
unlink(klitirqd);
cfifo_job_arrival(klitirqd);
}
else
{
__set_priority_inheritance(klitirqd, NULL);
}
tsk_rt(old_owner)->cur_klitirqd = NULL;
raw_spin_unlock(&cluster->cfifo_lock);
}
#endif // CONFIG_LITMUS_SOFTIRQD
/* ******************** KFMLP support ********************** */
/* struct for semaphore with priority inheritance */
struct kfmlp_queue
{
wait_queue_head_t wait;
struct task_struct* owner;
struct task_struct* hp_waiter;
int count; /* number of waiters + holder */
};
struct kfmlp_semaphore
{
struct litmus_lock litmus_lock;
spinlock_t lock;
int num_resources; /* aka k */
struct kfmlp_queue *queues; /* array */
struct kfmlp_queue *shortest_queue; /* pointer to shortest queue */
};
static inline struct kfmlp_semaphore* kfmlp_from_lock(struct litmus_lock* lock)
{
return container_of(lock, struct kfmlp_semaphore, litmus_lock);
}
static inline int kfmlp_get_idx(struct kfmlp_semaphore* sem,
struct kfmlp_queue* queue)
{
return (queue - &sem->queues[0]);
}
static inline struct kfmlp_queue* kfmlp_get_queue(struct kfmlp_semaphore* sem,
struct task_struct* holder)
{
int i;
for(i = 0; i < sem->num_resources; ++i)
if(sem->queues[i].owner == holder)
return(&sem->queues[i]);
return(NULL);
}
/* caller is responsible for locking */
static struct task_struct* kfmlp_find_hp_waiter(struct kfmlp_queue *kqueue,
struct task_struct *skip)
{
struct list_head *pos;
struct task_struct *queued, *found = NULL;
list_for_each(pos, &kqueue->wait.task_list) {
queued = (struct task_struct*) list_entry(pos, wait_queue_t,
task_list)->private;
/* Compare task prios, find high prio task. */
if (queued != skip && fifo_higher_prio(queued, found))
found = queued;
}
return found;
}
static inline struct kfmlp_queue* kfmlp_find_shortest(
struct kfmlp_semaphore* sem,
struct kfmlp_queue* search_start)
{
// we start our search at search_start instead of at the beginning of the
// queue list to load-balance across all resources.
struct kfmlp_queue* step = search_start;
struct kfmlp_queue* shortest = sem->shortest_queue;
do
{
step = (step+1 != &sem->queues[sem->num_resources]) ?
step+1 : &sem->queues[0];
if(step->count < shortest->count)
{
shortest = step;
if(step->count == 0)
break; /* can't get any shorter */
}
}while(step != search_start);
return(shortest);
}
static struct task_struct* kfmlp_remove_hp_waiter(struct kfmlp_semaphore* sem)
{
/* must hold sem->lock */
struct kfmlp_queue *my_queue = NULL;
struct task_struct *max_hp = NULL;
struct list_head *pos;
struct task_struct *queued;
int i;
for(i = 0; i < sem->num_resources; ++i)
{
if( (sem->queues[i].count > 1) &&
((my_queue == NULL) ||
(fifo_higher_prio(sem->queues[i].hp_waiter, my_queue->hp_waiter))) )
{
my_queue = &sem->queues[i];
}
}
if(my_queue)
{
cfifo_domain_t* cluster;
max_hp = my_queue->hp_waiter;
BUG_ON(!max_hp);
TRACE_CUR("queue %d: stealing %s/%d from queue %d\n",
kfmlp_get_idx(sem, my_queue),
max_hp->comm, max_hp->pid,
kfmlp_get_idx(sem, my_queue));
my_queue->hp_waiter = kfmlp_find_hp_waiter(my_queue, max_hp);
/*
if(my_queue->hp_waiter)
TRACE_CUR("queue %d: new hp_waiter is %s/%d\n",
kfmlp_get_idx(sem, my_queue),
my_queue->hp_waiter->comm,
my_queue->hp_waiter->pid);
else
TRACE_CUR("queue %d: new hp_waiter is %p\n",
kfmlp_get_idx(sem, my_queue), NULL);
*/
cluster = task_cpu_cluster(max_hp);
raw_spin_lock(&cluster->cfifo_lock);
/*
if(my_queue->owner)
TRACE_CUR("queue %d: owner is %s/%d\n",
kfmlp_get_idx(sem, my_queue),
my_queue->owner->comm,
my_queue->owner->pid);
else
TRACE_CUR("queue %d: owner is %p\n",
kfmlp_get_idx(sem, my_queue),
NULL);
*/
if(tsk_rt(my_queue->owner)->inh_task == max_hp)
{
__clear_priority_inheritance(my_queue->owner);
if(my_queue->hp_waiter != NULL)
{
__set_priority_inheritance(my_queue->owner, my_queue->hp_waiter);
}
}
raw_spin_unlock(&cluster->cfifo_lock);
list_for_each(pos, &my_queue->wait.task_list)
{
queued = (struct task_struct*) list_entry(pos, wait_queue_t,
task_list)->private;
/* Compare task prios, find high prio task. */
if (queued == max_hp)
{
/*
TRACE_CUR("queue %d: found entry in wait queue. REMOVING!\n",
kfmlp_get_idx(sem, my_queue));
*/
__remove_wait_queue(&my_queue->wait,
list_entry(pos, wait_queue_t, task_list));
break;
}
}
--(my_queue->count);
}
return(max_hp);
}
int cfifo_kfmlp_lock(struct litmus_lock* l)
{
struct task_struct* t = current;
struct kfmlp_semaphore *sem = kfmlp_from_lock(l);
struct kfmlp_queue* my_queue;
wait_queue_t wait;
unsigned long flags;
if (!is_realtime(t))
return -EPERM;
spin_lock_irqsave(&sem->lock, flags);
my_queue = sem->shortest_queue;
if (my_queue->owner) {
/* resource is not free => must suspend and wait */
TRACE_CUR("queue %d: Resource is not free => must suspend and wait.\n",
kfmlp_get_idx(sem, my_queue));
init_waitqueue_entry(&wait, t);
/* FIXME: interruptible would be nice some day */
set_task_state(t, TASK_UNINTERRUPTIBLE);
__add_wait_queue_tail_exclusive(&my_queue->wait, &wait);
/* check if we need to activate priority inheritance */
if (fifo_higher_prio(t, my_queue->hp_waiter))
{
my_queue->hp_waiter = t;
if (fifo_higher_prio(t, my_queue->owner))
{
set_priority_inheritance(my_queue->owner, my_queue->hp_waiter);
}
}
++(my_queue->count);
sem->shortest_queue = kfmlp_find_shortest(sem, my_queue);
/* release lock before sleeping */
spin_unlock_irqrestore(&sem->lock, flags);
/* We depend on the FIFO order. Thus, we don't need to recheck
* when we wake up; we are guaranteed to have the lock since
* there is only one wake up per release (or steal).
*/
schedule();
if(my_queue->owner == t)
{
TRACE_CUR("queue %d: acquired through waiting\n",
kfmlp_get_idx(sem, my_queue));
}
else
{
/* this case may happen if our wait entry was stolen
between queues. record where we went.*/
my_queue = kfmlp_get_queue(sem, t);
BUG_ON(!my_queue);
TRACE_CUR("queue %d: acquired through stealing\n",
kfmlp_get_idx(sem, my_queue));
}
}
else
{
TRACE_CUR("queue %d: acquired immediately\n",
kfmlp_get_idx(sem, my_queue));
my_queue->owner = t;
++(my_queue->count);
sem->shortest_queue = kfmlp_find_shortest(sem, my_queue);
spin_unlock_irqrestore(&sem->lock, flags);
}
return kfmlp_get_idx(sem, my_queue);
}
int cfifo_kfmlp_unlock(struct litmus_lock* l)
{
struct task_struct *t = current, *next;
struct kfmlp_semaphore *sem = kfmlp_from_lock(l);
struct kfmlp_queue *my_queue;
unsigned long flags;
int err = 0;
spin_lock_irqsave(&sem->lock, flags);
my_queue = kfmlp_get_queue(sem, t);
if (!my_queue) {
err = -EINVAL;
goto out;
}
/* check if there are jobs waiting for this resource */
next = __waitqueue_remove_first(&my_queue->wait);
if (next) {
/*
TRACE_CUR("queue %d: ASSIGNING %s/%d as owner - next\n",
kfmlp_get_idx(sem, my_queue),
next->comm, next->pid);
*/
/* next becomes the resouce holder */
my_queue->owner = next;
--(my_queue->count);
if(my_queue->count < sem->shortest_queue->count)
{
sem->shortest_queue = my_queue;
}
TRACE_CUR("queue %d: lock ownership passed to %s/%d\n",
kfmlp_get_idx(sem, my_queue), next->comm, next->pid);
/* determine new hp_waiter if necessary */
if (next == my_queue->hp_waiter) {
TRACE_TASK(next, "was highest-prio waiter\n");
/* next has the highest priority --- it doesn't need to
* inherit. However, we need to make sure that the
* next-highest priority in the queue is reflected in
* hp_waiter. */
my_queue->hp_waiter = kfmlp_find_hp_waiter(my_queue, next);
if (my_queue->hp_waiter)
TRACE_TASK(my_queue->hp_waiter, "queue %d: is new highest-prio waiter\n", kfmlp_get_idx(sem, my_queue));
else
TRACE("queue %d: no further waiters\n", kfmlp_get_idx(sem, my_queue));
} else {
/* Well, if next is not the highest-priority waiter,
* then it ought to inherit the highest-priority
* waiter's priority. */
set_priority_inheritance(next, my_queue->hp_waiter);
}
/* wake up next */
wake_up_process(next);
}
else
{
TRACE_CUR("queue %d: looking to steal someone...\n", kfmlp_get_idx(sem, my_queue));
next = kfmlp_remove_hp_waiter(sem); /* returns NULL if nothing to steal */
/*
if(next)
TRACE_CUR("queue %d: ASSIGNING %s/%d as owner - steal\n",
kfmlp_get_idx(sem, my_queue),
next->comm, next->pid);
*/
my_queue->owner = next;
if(next)
{
TRACE_CUR("queue %d: lock ownership passed to %s/%d (which was stolen)\n",
kfmlp_get_idx(sem, my_queue),
next->comm, next->pid);
/* wake up next */
wake_up_process(next);
}
else
{
TRACE_CUR("queue %d: no one to steal.\n", kfmlp_get_idx(sem, my_queue));
--(my_queue->count);
if(my_queue->count < sem->shortest_queue->count)
{
sem->shortest_queue = my_queue;
}
}
}
/* we lose the benefit of priority inheritance (if any) */
if (tsk_rt(t)->inh_task)
clear_priority_inheritance(t);
out:
spin_unlock_irqrestore(&sem->lock, flags);
return err;
}
int cfifo_kfmlp_close(struct litmus_lock* l)
{
struct task_struct *t = current;
struct kfmlp_semaphore *sem = kfmlp_from_lock(l);
struct kfmlp_queue *my_queue;
unsigned long flags;
int owner;
spin_lock_irqsave(&sem->lock, flags);
my_queue = kfmlp_get_queue(sem, t);
owner = (my_queue) ? (my_queue->owner == t) : 0;
spin_unlock_irqrestore(&sem->lock, flags);
if (owner)
cfifo_kfmlp_unlock(l);
return 0;
}
void cfifo_kfmlp_free(struct litmus_lock* l)
{
struct kfmlp_semaphore *sem = kfmlp_from_lock(l);
kfree(sem->queues);
kfree(sem);
}
static struct litmus_lock_ops cfifo_kfmlp_lock_ops = {
.close = cfifo_kfmlp_close,
.lock = cfifo_kfmlp_lock,
.unlock = cfifo_kfmlp_unlock,
.deallocate = cfifo_kfmlp_free,
};
static struct litmus_lock* cfifo_new_kfmlp(void* __user arg, int* ret_code)
{
struct kfmlp_semaphore* sem;
int num_resources = 0;
int i;
if(!access_ok(VERIFY_READ, arg, sizeof(num_resources)))
{
*ret_code = -EINVAL;
return(NULL);
}
if(__copy_from_user(&num_resources, arg, sizeof(num_resources)))
{
*ret_code = -EINVAL;
return(NULL);
}
if(num_resources < 1)
{
*ret_code = -EINVAL;
return(NULL);
}
sem = kmalloc(sizeof(*sem), GFP_KERNEL);
if(!sem)
{
*ret_code = -ENOMEM;
return NULL;
}
sem->queues = kmalloc(sizeof(struct kfmlp_queue)*num_resources, GFP_KERNEL);
if(!sem->queues)
{
kfree(sem);
*ret_code = -ENOMEM;
return NULL;
}
sem->litmus_lock.ops = &cfifo_kfmlp_lock_ops;
spin_lock_init(&sem->lock);
sem->num_resources = num_resources;
for(i = 0; i < num_resources; ++i)
{
sem->queues[i].owner = NULL;
sem->queues[i].hp_waiter = NULL;
init_waitqueue_head(&sem->queues[i].wait);
sem->queues[i].count = 0;
}
sem->shortest_queue = &sem->queues[0];
*ret_code = 0;
return &sem->litmus_lock;
}
/* **** lock constructor **** */
static long cfifo_allocate_lock(struct litmus_lock **lock, int type,
void* __user arg)
{
int err = -ENXIO;
/* C-FIFO currently only supports the FMLP for global resources
WITHIN a given cluster. DO NOT USE CROSS-CLUSTER! */
switch (type) {
case KFMLP_SEM:
*lock = cfifo_new_kfmlp(arg, &err);
break;
};
return err;
}
#endif // CONFIG_LITMUS_LOCKING
/* total number of cluster */
static int num_clusters;
/* we do not support cluster of different sizes */
static unsigned int cluster_size;
#ifdef VERBOSE_INIT
static void print_cluster_topology(cpumask_var_t mask, int cpu)
{
int chk;
char buf[255];
chk = cpulist_scnprintf(buf, 254, mask);
buf[chk] = '\0';
printk(KERN_INFO "CPU = %d, shared cpu(s) = %s\n", cpu, buf);
}
#endif
static int clusters_allocated = 0;
static void cleanup_cfifo(void)
{
int i;
if (clusters_allocated) {
for (i = 0; i < num_clusters; i++) {
kfree(cfifo[i].cpus);
kfree(cfifo[i].heap_node);
free_cpumask_var(cfifo[i].cpu_map);
}
kfree(cfifo);
}
}
static long cfifo_activate_plugin(void)
{
int i, j, cpu, ccpu, cpu_count;
cpu_entry_t *entry;
cpumask_var_t mask;
int chk = 0;
/* de-allocate old clusters, if any */
cleanup_cfifo();
printk(KERN_INFO "C-FIFO: Activate Plugin, cluster configuration = %d\n",
cluster_config);
/* need to get cluster_size first */
if(!zalloc_cpumask_var(&mask, GFP_ATOMIC))
return -ENOMEM;
if (unlikely(cluster_config == GLOBAL_CLUSTER)) {
cluster_size = num_online_cpus();
} else {
chk = get_shared_cpu_map(mask, 0, cluster_config);
if (chk) {
/* if chk != 0 then it is the max allowed index */
printk(KERN_INFO "C-FIFO: Cluster configuration = %d "
"is not supported on this hardware.\n",
cluster_config);
/* User should notice that the configuration failed, so
* let's bail out. */
return -EINVAL;
}
cluster_size = cpumask_weight(mask);
}
if ((num_online_cpus() % cluster_size) != 0) {
/* this can't be right, some cpus are left out */
printk(KERN_ERR "C-FIFO: Trying to group %d cpus in %d!\n",
num_online_cpus(), cluster_size);
return -1;
}
num_clusters = num_online_cpus() / cluster_size;
printk(KERN_INFO "C-FIFO: %d cluster(s) of size = %d\n",
num_clusters, cluster_size);
/* initialize clusters */
cfifo = kmalloc(num_clusters * sizeof(cfifo_domain_t), GFP_ATOMIC);
for (i = 0; i < num_clusters; i++) {
cfifo[i].cpus = kmalloc(cluster_size * sizeof(cpu_entry_t),
GFP_ATOMIC);
cfifo[i].heap_node = kmalloc(
cluster_size * sizeof(struct bheap_node),
GFP_ATOMIC);
bheap_init(&(cfifo[i].cpu_heap));
fifo_domain_init(&(cfifo[i].domain), NULL, cfifo_release_jobs);
#ifdef CONFIG_LITMUS_PAI_SOFTIRQD
cfifo[i].pending_tasklets.head = NULL;
cfifo[i].pending_tasklets.tail = &(cfifo[i].pending_tasklets.head);
#endif
if(!zalloc_cpumask_var(&cfifo[i].cpu_map, GFP_ATOMIC))
return -ENOMEM;
}
/* cycle through cluster and add cpus to them */
for (i = 0; i < num_clusters; i++) {
for_each_online_cpu(cpu) {
/* check if the cpu is already in a cluster */
for (j = 0; j < num_clusters; j++)
if (cpumask_test_cpu(cpu, cfifo[j].cpu_map))
break;
/* if it is in a cluster go to next cpu */
if (j < num_clusters &&
cpumask_test_cpu(cpu, cfifo[j].cpu_map))
continue;
/* this cpu isn't in any cluster */
/* get the shared cpus */
if (unlikely(cluster_config == GLOBAL_CLUSTER))
cpumask_copy(mask, cpu_online_mask);
else
get_shared_cpu_map(mask, cpu, cluster_config);
cpumask_copy(cfifo[i].cpu_map, mask);
#ifdef VERBOSE_INIT
print_cluster_topology(mask, cpu);
#endif
/* add cpus to current cluster and init cpu_entry_t */
cpu_count = 0;
for_each_cpu(ccpu, cfifo[i].cpu_map) {
entry = &per_cpu(cfifo_cpu_entries, ccpu);
cfifo[i].cpus[cpu_count] = entry;
atomic_set(&entry->will_schedule, 0);
entry->cpu = ccpu;
entry->cluster = &cfifo[i];
entry->hn = &(cfifo[i].heap_node[cpu_count]);
bheap_node_init(&entry->hn, entry);
cpu_count++;
entry->linked = NULL;
entry->scheduled = NULL;
update_cpu_position(entry);
}
/* done with this cluster */
break;
}
}
#ifdef CONFIG_LITMUS_SOFTIRQD
{
/* distribute the daemons evenly across the clusters. */
int* affinity = kmalloc(NR_LITMUS_SOFTIRQD * sizeof(int), GFP_ATOMIC);
int num_daemons_per_cluster = NR_LITMUS_SOFTIRQD / num_clusters;
int left_over = NR_LITMUS_SOFTIRQD % num_clusters;
int daemon = 0;
for(i = 0; i < num_clusters; ++i)
{
int num_on_this_cluster = num_daemons_per_cluster;
if(left_over)
{
++num_on_this_cluster;
--left_over;
}
for(j = 0; j < num_on_this_cluster; ++j)
{
// first CPU of this cluster
affinity[daemon++] = i*cluster_size;
}
}
spawn_klitirqd(affinity);
kfree(affinity);
}
#endif
#ifdef CONFIG_LITMUS_NVIDIA
init_nvidia_info();
#endif
free_cpumask_var(mask);
clusters_allocated = 1;
return 0;
}
/* Plugin object */
static struct sched_plugin cfifo_plugin __cacheline_aligned_in_smp = {
.plugin_name = "C-FIFO",
.finish_switch = cfifo_finish_switch,
.tick = cfifo_tick,
.task_new = cfifo_task_new,
.complete_job = complete_job,
.task_exit = cfifo_task_exit,
.schedule = cfifo_schedule,
.task_wake_up = cfifo_task_wake_up,
.task_block = cfifo_task_block,
.admit_task = cfifo_admit_task,
.activate_plugin = cfifo_activate_plugin,
#ifdef CONFIG_LITMUS_LOCKING
.allocate_lock = cfifo_allocate_lock,
.set_prio_inh = set_priority_inheritance,
.clear_prio_inh = clear_priority_inheritance,
#endif
#ifdef CONFIG_LITMUS_SOFTIRQD
.set_prio_inh_klitirqd = set_priority_inheritance_klitirqd,
.clear_prio_inh_klitirqd = clear_priority_inheritance_klitirqd,
#endif
#ifdef CONFIG_LITMUS_PAI_SOFTIRQD
.enqueue_pai_tasklet = enqueue_pai_tasklet,
.run_tasklets = run_tasklets,
#endif
};
static struct proc_dir_entry *cluster_file = NULL, *cfifo_dir = NULL;
static int __init init_cfifo(void)
{
int err, fs;
err = register_sched_plugin(&cfifo_plugin);
if (!err) {
fs = make_plugin_proc_dir(&cfifo_plugin, &cfifo_dir);
if (!fs)
cluster_file = create_cluster_file(cfifo_dir, &cluster_config);
else
printk(KERN_ERR "Could not allocate C-FIFO procfs dir.\n");
}
return err;
}
static void clean_cfifo(void)
{
cleanup_cfifo();
if (cluster_file)
remove_proc_entry("cluster", cfifo_dir);
if (cfifo_dir)
remove_plugin_proc_dir(&cfifo_plugin);
}
module_init(init_cfifo);
module_exit(clean_cfifo);
