linux/kernel/sched_rt.c, branch v2.6.24

sched: rt: account the cpu time during the tick

2007-12-20T14:01:17Z

Realtime tasks would not account their runtime during ticks. Which would lead to: struct sched_param param = { .sched_priority = 10 }; pthread_setschedparam(pthread_self(), SCHED_FIFO, ¶m); while (1) ; Not showing up in top. Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner

sched: cpu accounting controller (V2)

2007-12-02T19:04:49Z

Commit cfb5285660aad4931b2ebbfa902ea48a37dfffa1 removed a useful feature for us, which provided a cpu accounting resource controller. This feature would be useful if someone wants to group tasks only for accounting purpose and doesnt really want to exercise any control over their cpu consumption. The patch below reintroduces the feature. It is based on Paul Menage's original patch (Commit 62d0df64065e7c135d0002f069444fbdfc64768f), with these differences: - Removed load average information. I felt it needs more thought (esp to deal with SMP and virtualized platforms) and can be added for 2.6.25 after more discussions. - Convert group cpu usage to be nanosecond accurate (as rest of the cfs stats are) and invoke cpuacct_charge() from the respective scheduler classes - Make accounting scalable on SMP systems by splitting the usage counter to be per-cpu - Move the code from kernel/cpu_acct.c to kernel/sched.c (since the code is not big enough to warrant a new file and also this rightly needs to live inside the scheduler. Also things like accessing rq->lock while reading cpu usage becomes easier if the code lived in kernel/sched.c) The patch also modifies the cpu controller not to provide the same accounting information. Tested-by: Balbir Singh Tested the patches on top of 2.6.24-rc3. The patches work fine. Ran some simple tests like cpuspin (spin on the cpu), ran several tasks in the same group and timed them. Compared their time stamps with cpuacct.usage. Signed-off-by: Srivatsa Vaddagiri Signed-off-by: Balbir Singh Signed-off-by: Ingo Molnar

sched: isolate SMP balancing code a bit more

2007-10-24T16:23:51Z

At the moment, a lot of load balancing code that is irrelevant to non SMP systems gets included during non SMP builds. This patch addresses this issue and reduces the binary size on non SMP systems: text data bss dec hex filename 10983 28 1192 12203 2fab sched.o.before 10739 28 1192 11959 2eb7 sched.o.after Signed-off-by: Peter Williams Signed-off-by: Ingo Molnar

sched: reduce balance-tasks overhead

2007-10-24T16:23:51Z

At the moment, balance_tasks() provides low level functionality for both move_tasks() and move_one_task() (indirectly) via the load_balance() function (in the sched_class interface) which also provides dual functionality. This dual functionality complicates the interfaces and internal mechanisms and makes the run time overhead of operations that are called with two run queue locks held. This patch addresses this issue and reduces the overhead of these operations. Signed-off-by: Peter Williams Signed-off-by: Ingo Molnar

sched: tidy up SCHED_RR

2007-10-15T15:00:13Z

- make timeslices of SCHED_RR tasks constant and not dependent on task's static_prio [1] ; - remove obsolete code (timeslice related bits); - make sched_rr_get_interval() return something more meaningful [2] for SCHED_OTHER tasks. [1] according to the following link, it's not compliant with SUSv3 (not sure though, what is the reference for us :-) http://lkml.org/lkml/2007/3/7/656 [2] the interval is dynamic and can be depicted as follows "should a task be one of the runnable tasks at this particular moment, it would expect to run for this interval of time before being re-scheduled by the scheduler tick". (i.e. it's more precise if a task is runnable at the moment) yeah, this seems to require task_rq_lock/unlock() but this is not a hot path. results: (SCHED_FIFO) dimm@earth:~/storage/prog$ sudo chrt -f 10 ./rr_interval time_slice: 0 : 0 (SCHED_RR) dimm@earth:~/storage/prog$ sudo chrt 10 ./rr_interval time_slice: 0 : 99984800 (SCHED_NORMAL) dimm@earth:~/storage/prog$ ./rr_interval time_slice: 0 : 19996960 (SCHED_NORMAL + a cpu_hog of similar 'weight' on the same CPU --- so should be a half of the previous result) dimm@earth:~/storage/prog$ taskset 1 ./rr_interval time_slice: 0 : 9998480 Signed-off-by: Dmitry Adamushko Signed-off-by: Ingo Molnar

sched: uninline scheduler

2007-10-15T15:00:13Z

* save ~300 bytes * activate_idle_task() was moved to avoid a warning bloat-o-meter output: add/remove: 6/0 grow/shrink: 0/16 up/down: 438/-733 (-295) <=== function old new delta __enqueue_entity - 165 +165 finish_task_switch - 110 +110 update_curr_rt - 79 +79 __load_balance_iterator - 32 +32 __task_rq_unlock - 28 +28 find_process_by_pid - 24 +24 do_sched_setscheduler 133 123 -10 sys_sched_rr_get_interval 176 165 -11 sys_sched_getparam 156 145 -11 normalize_rt_tasks 482 470 -12 sched_getaffinity 112 99 -13 sys_sched_getscheduler 86 72 -14 sched_setaffinity 226 212 -14 sched_setscheduler 666 642 -24 load_balance_start_fair 33 9 -24 load_balance_next_fair 33 9 -24 dequeue_task_rt 133 67 -66 put_prev_task_rt 97 28 -69 schedule_tail 133 50 -83 schedule 682 594 -88 enqueue_entity 499 366 -133 task_new_fair 317 180 -137 Signed-off-by: Alexey Dobriyan Signed-off-by: Ingo Molnar

sched: mark scheduling classes as const

2007-10-15T15:00:12Z

mark scheduling classes as const. The speeds up the code a bit and shrinks it: text data bss dec hex filename 40027 4018 292 44337 ad31 sched.o.before 40190 3842 292 44324 ad24 sched.o.after Signed-off-by: Ingo Molnar Reviewed-by: Thomas Gleixner

sched: revert recent removal of set_curr_task()

2007-10-15T15:00:08Z

Revert removal of set_curr_task. Use put_prev_task/set_curr_task when changing groups/policies Signed-off-by: Srivatsa Vaddagiri < vatsa@linux.vnet.ibm.com> Signed-off-by: Dhaval Giani Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra

sched: rework enqueue/dequeue_entity() to get rid of set_curr_task()

2007-10-15T15:00:08Z

rework enqueue/dequeue_entity() to get rid of sched_class::set_curr_task(). This simplifies sched_setscheduler(), rt_mutex_setprio() and sched_move_tasks(). text data bss dec hex filename 24330 2734 20 27084 69cc sched.o.before 24233 2730 20 26983 6967 sched.o.after Signed-off-by: Dmitry Adamushko Signed-off-by: Srivatsa Vaddagiri Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra Reviewed-by: Thomas Gleixner

sched: simplify sched_class::yield_task()

2007-10-15T15:00:08Z

the 'p' (task_struct) parameter in the sched_class :: yield_task() is redundant as the caller is always the 'current'. Get rid of it. text data bss dec hex filename 24341 2734 20 27095 69d7 sched.o.before 24330 2734 20 27084 69cc sched.o.after Signed-off-by: Dmitry Adamushko Signed-off-by: Ingo Molnar Signed-off-by: Peter Zijlstra Reviewed-by: Thomas Gleixner