1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
|
/*
* Definition of the scheduler plugin interface.
*
*/
#ifndef _LINUX_RT_PARAM_H_
#define _LINUX_RT_PARAM_H_
/* Litmus time type. */
typedef unsigned long long lt_t;
static inline int lt_after(lt_t a, lt_t b)
{
return ((long long) b) - ((long long) a) < 0;
}
#define lt_before(a, b) lt_after(b, a)
static inline int lt_after_eq(lt_t a, lt_t b)
{
return ((long long) a) - ((long long) b) >= 0;
}
#define lt_before_eq(a, b) lt_after_eq(b, a)
/* different types of clients */
typedef enum {
RT_CLASS_HARD,
RT_CLASS_SOFT,
RT_CLASS_BEST_EFFORT
} task_class_t;
typedef enum {
NO_ENFORCEMENT, /* job may overrun unhindered */
QUANTUM_ENFORCEMENT, /* budgets are only checked on quantum boundaries */
PRECISE_ENFORCEMENT /* NOT IMPLEMENTED - enforced with hrtimers */
} budget_policy_t;
/* The parameters for the EDF-WM semi-partitioned scheduler.
* Each task may be split across multiple cpus. Each per-cpu allocation
* is called a 'slice'.
*/
#define MAX_EDF_WM_SLICES NR_CPUS
#define MIN_EDF_WM_SLICE_SIZE 1000000 /* 1 millisecond */
struct edf_wm_slice {
/* on which CPU is this slice allocated */
unsigned int cpu;
/* relative deadline from job release (not from slice release!) */
lt_t deadline;
/* budget of this slice; must be precisely enforced */
lt_t budget;
/* offset of this slice relative to the job release */
lt_t offset;
};
/* If a job is not sliced across multiple CPUs, then
* count is set to zero and none of the slices is used.
* This implies that count == 1 is illegal.
*/
struct edf_wm_params {
/* enumeration of all slices */
struct edf_wm_slice slices[MAX_EDF_WM_SLICES];
/* how many slices are defined? */
unsigned int count;
};
struct rt_task {
lt_t exec_cost;
lt_t period;
lt_t phase;
unsigned int cpu;
task_class_t cls;
budget_policy_t budget_policy; /* ignored by pfair */
/* parameters used by the semi-partitioned algorithms */
union {
/* EDF-WM; defined in sched_edf_wm.c */
struct edf_wm_params wm;
} semi_part;
};
/* The definition of the data that is shared between the kernel and real-time
* tasks via a shared page (see litmus/ctrldev.c).
*
* WARNING: User space can write to this, so don't trust
* the correctness of the fields!
*
* This servees two purposes: to enable efficient signaling
* of non-preemptive sections (user->kernel) and
* delayed preemptions (kernel->user), and to export
* some real-time relevant statistics such as preemption and
* migration data to user space. We can't use a device to export
* statistics because we want to avoid system call overhead when
* determining preemption/migration overheads).
*/
struct control_page {
/* Is the task currently in a non-preemptive section? */
int np_flag;
/* Should the task call into the kernel when it leaves
* its non-preemptive section? */
int delayed_preemption;
/* to be extended */
};
/* don't export internal data structures to user space (liblitmus) */
#ifdef __KERNEL__
struct _rt_domain;
struct bheap_node;
struct release_heap;
struct rt_job {
/* Time instant the the job was or will be released. */
lt_t release;
/* What is the current deadline? */
lt_t deadline;
/* How much service has this job received so far? */
lt_t exec_time;
/* Which job is this. This is used to let user space
* specify which job to wait for, which is important if jobs
* overrun. If we just call sys_sleep_next_period() then we
* will unintentionally miss jobs after an overrun.
*
* Increase this sequence number when a job is released.
*/
unsigned int job_no;
};
struct pfair_param;
/* RT task parameters for scheduling extensions
* These parameters are inherited during clone and therefore must
* be explicitly set up before the task set is launched.
*/
struct rt_param {
/* is the task sleeping? */
unsigned int flags:8;
/* do we need to check for srp blocking? */
unsigned int srp_non_recurse:1;
/* is the task present? (true if it can be scheduled) */
unsigned int present:1;
/* user controlled parameters */
struct rt_task task_params;
/* timing parameters */
struct rt_job job_params;
/* task representing the current "inherited" task
* priority, assigned by inherit_priority and
* return priority in the scheduler plugins.
* could point to self if PI does not result in
* an increased task priority.
*/
struct task_struct* inh_task;
#ifdef CONFIG_NP_SECTION
/* For the FMLP under PSN-EDF, it is required to make the task
* non-preemptive from kernel space. In order not to interfere with
* user space, this counter indicates the kernel space np setting.
* kernel_np > 0 => task is non-preemptive
*/
unsigned int kernel_np;
#endif
/* This field can be used by plugins to store where the task
* is currently scheduled. It is the responsibility of the
* plugin to avoid race conditions.
*
* This used by GSN-EDF and PFAIR.
*/
volatile int scheduled_on;
/* Is the stack of the task currently in use? This is updated by
* the LITMUS core.
*
* Be careful to avoid deadlocks!
*/
volatile int stack_in_use;
/* This field can be used by plugins to store where the task
* is currently linked. It is the responsibility of the plugin
* to avoid race conditions.
*
* Used by GSN-EDF.
*/
volatile int linked_on;
/* PFAIR/PD^2 state. Allocated on demand. */
struct pfair_param* pfair;
/* Fields saved before BE->RT transition.
*/
int old_policy;
int old_prio;
/* ready queue for this task */
struct _rt_domain* domain;
/* heap element for this task
*
* Warning: Don't statically allocate this node. The heap
* implementation swaps these between tasks, thus after
* dequeuing from a heap you may end up with a different node
* then the one you had when enqueuing the task. For the same
* reason, don't obtain and store references to this node
* other than this pointer (which is updated by the heap
* implementation).
*/
struct bheap_node* heap_node;
struct release_heap* rel_heap;
/* Used by rt_domain to queue task in release list.
*/
struct list_head list;
/* Pointer to the page shared between userspace and kernel. */
struct control_page * ctrl_page;
/* runtime info for the semi-part plugins */
union {
struct {
/* at which exec time did the current slice start? */
lt_t exec_time;
/* cached job parameters */
lt_t job_release, job_deadline;
/* pointer to the current slice */
struct edf_wm_slice* slice;
} wm;
} semi_part;
};
/* Possible RT flags */
#define RT_F_RUNNING 0x00000000
#define RT_F_SLEEP 0x00000001
#define RT_F_EXIT_SEM 0x00000008
#endif
#endif
|
