- 20 4月, 2008 3 次提交
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由 Mike Travis 提交于
Add a new function that accepts a pointer to the "newly allowed cpus" cpumask argument. int set_cpus_allowed_ptr(struct task_struct *p, const cpumask_t *new_mask) The current set_cpus_allowed() function is modified to use the above but this does not result in an ABI change. And with some compiler optimization help, it may not introduce any additional overhead. Additionally, to enforce the read only nature of the new_mask arg, the "const" property is migrated to sub-functions called by set_cpus_allowed. This silences compiler warnings. Signed-off-by: NMike Travis <travis@sgi.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Currently the rt group scheduling does a per cpu runtime limit, however the rt load balancer makes no guarantees about an equal spread of real- time tasks, just that at any one time, the highest priority tasks run. Solve this by making the runtime limit a global property by borrowing excessive runtime from the other cpus once the local limit runs out. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Various SMP balancing algorithms require that the bandwidth period run in sync. Possible improvements are moving the rt_bandwidth thing into root_domain and keeping a span per rt_bandwidth which marks throttled cpus. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 07 3月, 2008 1 次提交
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由 Steven Rostedt 提交于
Sripathi Kodi reported a crash in the -rt kernel: https://bugzilla.redhat.com/show_bug.cgi?id=435674 this is due to a place that can reschedule a task without holding the tasks runqueue lock. This was caused by the RT balancing code that pulls RT tasks to the current run queue and will reschedule the current task. There's a slight chance that the pulling of the RT tasks will release the current runqueue's lock and retake it (in the double_lock_balance). During this time that the runqueue is released, the current task can migrate to another runqueue. In the prio_changed_rt code, after the pull, if the current task is of lesser priority than one of the RT tasks pulled, resched_task is called on the current task. If the current task had migrated in that small window, resched_task will be called without holding the runqueue lock for the runqueue that the task is on. This race condition also exists in the mainline kernel and this patch adds a check to make sure the task hasn't migrated before calling resched_task. Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Tested-by: NSripathi Kodi <sripathik@in.ibm.com> Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 05 3月, 2008 1 次提交
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由 Peter Zijlstra 提交于
The following commits cause a number of regressions: commit 58e2d4ca Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Date: Fri Jan 25 21:08:00 2008 +0100 sched: group scheduling, change how cpu load is calculated commit 6b2d7700 Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Date: Fri Jan 25 21:08:00 2008 +0100 sched: group scheduler, fix fairness of cpu bandwidth allocation for task groups Namely: - very frequent wakeups on SMP, reported by PowerTop users. - cacheline trashing on (large) SMP - some latencies larger than 500ms While there is a mergeable patch to fix the latter, the former issues are not fixable in a manner suitable for .25 (we're at -rc3 now). Hence we revert them and try again in v2.6.26. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Tested-by: NAlexey Zaytsev <alexey.zaytsev@gmail.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 13 2月, 2008 3 次提交
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由 Peter Zijlstra 提交于
Make the rt group scheduler compile time configurable. Keep it experimental for now. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Change the rt_ratio interface to rt_runtime_us, to match rt_period_us. This avoids picking a granularity for the ratio. Extend the /sys/kernel/uids/<uid>/ interface to allow setting the group's rt_runtime. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Steven mentioned the fun case where a lock holding task will be throttled. Simple fix: allow groups that have boosted tasks to run anyway. If a runnable task in a throttled group gets boosted the dequeue/enqueue done by rt_mutex_setprio() is enough to unthrottle the group. This is ofcourse not quite correct. Two possible ways forward are: - second prio array for boosted tasks - boost to a prio ceiling (this would also work for deadline scheduling) Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 26 1月, 2008 32 次提交
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由 Dmitry Adamushko 提交于
looking at it one more time: (1) it looks to me that there is no need to call sched_rt_ratio_exceeded() from pick_next_rt_entity() - [ for CONFIG_FAIR_GROUP_SCHED ] queues with rt_rq->rt_throttled are not within this 'tree-like hierarchy' (or whatever we should call it :-) - there is also no need to re-check 'rt_rq->rt_time > ratio' at this point as 'rt_rq->rt_time' couldn't have been increased since the last call to update_curr_rt() (which obviously calls sched_rt_ratio_esceeded()) well, it might be that 'ratio' for this rt_rq has been re-configured (and the period over which this rt_rq was active has not yet been finished)... but I don't think we should really take this into account. (2) now pick_next_rt_entity() must never return NULL, so let's change pick_next_task_rt() accordingly. Signed-off-by: NDmitry Adamushko <dmitry.adamushko@gmail.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Remove the curious logic to set it_sched_expires in the future. It useless because rt.timeout wouldn't be incremented anyway. Explicity check for RLIM_INFINITY as a test programm that had a 1s soft limit and a inf hard limit would SIGKILL at 1s. This is because RLIM_INFINITY+d-1 is d-2. Signed-off-by: NPeter Zijlsta <a.p.zijlstra@chello.nl> CC: Michal Schmidt <mschmidt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Only reschedule if the new group has a higher prio task. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
We need to teach no_hz about the rt throttling because its tick driven. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Mike Galbraith 提交于
"goto out" is an odd way to spell "skip". Signed-off-by: NMike Galbraith <efault@gmx.de> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Extend group scheduling to also cover the realtime classes. It uses the time limiting introduced by the previous patch to allow multiple realtime groups. The hard time limit is required to keep behaviour deterministic. The algorithms used make the realtime scheduler O(tg), linear scaling wrt the number of task groups. This is the worst case behaviour I can't seem to get out of, the avg. case of the algorithms can be improved, I focused on correctness and worst case. [ akpm@linux-foundation.org: move side-effects out of BUG_ON(). ] Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Very simple time limit on the realtime scheduling classes. Allow the rq's realtime class to consume sched_rt_ratio of every sched_rt_period slice. If the class exceeds this quota the fair class will preempt the realtime class. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Use HR-timers (when available) to deliver an accurate preemption tick. The regular scheduler tick that runs at 1/HZ can be too coarse when nice level are used. The fairness system will still keep the cpu utilisation 'fair' by then delaying the task that got an excessive amount of CPU time but try to minimize this by delivering preemption points spot-on. The average frequency of this extra interrupt is sched_latency / nr_latency. Which need not be higher than 1/HZ, its just that the distribution within the sched_latency period is important. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Introduce a new rlimit that allows the user to set a runtime timeout on real-time tasks their slice. Once this limit is exceeded the task will receive SIGXCPU. So it measures runtime since the last sleep. Input and ideas by Thomas Gleixner and Lennart Poettering. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> CC: Lennart Poettering <mzxreary@0pointer.de> CC: Michael Kerrisk <mtk.manpages@googlemail.com> CC: Ulrich Drepper <drepper@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Move the task_struct members specific to rt scheduling together. A future optimization could be to put sched_entity and sched_rt_entity into a union. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
We had support for overlapping cpuset based rto logic in early prototypes that is no longer used, so remove it. Signed-off-by: NGregory Haskins <ghaskins@novell.com> Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
The overload set/clears were originally idempotent when this logic was first implemented. But that is no longer true due to the addition of the atomic counter and this logic was never updated to work properly with that change. So only adjust the overload state if it is actually changing to avoid getting out of sync. Signed-off-by: NGregory Haskins <ghaskins@novell.com> Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Steven Rostedt 提交于
Dmitry Adamushko found that the current implementation of the RT balancing code left out changes to the sched_setscheduler and rt_mutex_setprio. This patch addresses this issue by adding methods to the schedule classes to handle being switched out of (switched_from) and being switched into (switched_to) a sched_class. Also a method for changing of priorities is also added (prio_changed). This patch also removes some duplicate logic between rt_mutex_setprio and sched_setscheduler. Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Steven Rostedt 提交于
To make the main sched.c code more agnostic to the schedule classes. Instead of having specific hooks in the schedule code for the RT class balancing. They are replaced with a pre_schedule, post_schedule and task_wake_up methods. These methods may be used by any of the classes but currently, only the sched_rt class implements them. Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
fix build bug in sched_rt.c:join/leave_domain and make them only be included on SMP builds. Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
We move the rt-overload data as the first global to per-domain reclassification. This limits the scope of overload related cache-line bouncing to stay with a specified partition instead of affecting all cpus in the system. Finally, we limit the scope of find_lowest_cpu searches to the domain instead of the entire system. Note that we would always respect domain boundaries even without this patch, but we first would scan potentially all cpus before whittling the list down. Now we can avoid looking at RQs that are out of scope, again reducing cache-line hits. Note: In some cases, task->cpus_allowed will effectively reduce our search to within our domain. However, I believe there are cases where the cpus_allowed mask may be all ones and therefore we err on the side of caution. If it can be optimized later, so be it. Signed-off-by: NGregory Haskins <ghaskins@novell.com> CC: Christoph Lameter <clameter@sgi.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
clean up schedule_balance_rt(). Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
clean up pull_rt_task(). Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
remove leftover debugging. Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
remove rt_overload() - it's an unnecessary indirection. Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
clean up whitespace damage and missing comments in kernel/sched_rt.c. Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
clean up overlong line in kernel/sched_debug.c. Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
clean up find_lock_lowest_rq(). Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Ingo Molnar 提交于
clean up pick_next_highest_task_rt(). Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Steven Rostedt 提交于
This patch removes several cpumask operations by keeping track of the first of the CPUS that is of the lowest priority. When the search for the lowest priority runqueue is completed, all the bits up to the first CPU with the lowest priority runqueue is cleared. Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
We can cheaply track the number of bits set in the cpumask for the lowest priority CPUs. Therefore, compute the mask's weight and use it to skip the optimal domain search logic when there is only one CPU available. Signed-off-by: NGregory Haskins <ghaskins@novell.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
We don't need to bother searching if the task cannot be migrated Signed-off-by: NGregory Haskins <ghaskins@novell.com> Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Steven Rostedt 提交于
This patch changes the searching for a run queue by a waking RT task to try to pick another runqueue if the currently running task is an RT task. The reason is that RT tasks behave different than normal tasks. Preempting a normal task to run a RT task to keep its cache hot is fine, because the preempted non-RT task may wait on that same runqueue to run again unless the migration thread comes along and pulls it off. RT tasks behave differently. If one is preempted, it makes an active effort to continue to run. So by having a high priority task preempt a lower priority RT task, that lower RT task will then quickly try to run on another runqueue. This will cause that lower RT task to replace its nice hot cache (and TLB) with a completely cold one. This is for the hope that the new high priority RT task will keep its cache hot. Remeber that this high priority RT task was just woken up. So it may likely have been sleeping for several milliseconds, and will end up with a cold cache anyway. RT tasks run till they voluntarily stop, or are preempted by a higher priority task. This means that it is unlikely that the woken RT task will have a hot cache to wake up to. So pushing off a lower RT task is just killing its cache for no good reason. Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
We have logic to detect whether the system has migratable tasks, but we are not using it when deciding whether to push tasks away. So we add support for considering this new information. Signed-off-by: NGregory Haskins <ghaskins@novell.com> Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
The current code base assumes a relatively flat CPU/core topology and will route RT tasks to any CPU fairly equally. In the real world, there are various toplogies and affinities that govern where a task is best suited to run with the smallest amount of overhead. NUMA and multi-core CPUs are prime examples of topologies that can impact cache performance. Fortunately, linux is already structured to represent these topologies via the sched_domains interface. So we change our RT router to consult a combination of topology and affinity policy to best place tasks during migration. Signed-off-by: NGregory Haskins <ghaskins@novell.com> Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
In the original patch series that Steven Rostedt and I worked on together, we both took different approaches to low-priority wakeup path. I utilized "pre-routing" (push the task away to a less important RQ before activating) approach, while Steve utilized a "post-routing" approach. The advantage of my approach is that you avoid the overhead of a wasted activate/deactivate cycle and peripherally related burdens. The advantage of Steve's method is that it neatly solves an issue preventing a "pull" optimization from being deployed. In the end, we ended up deploying Steve's idea. But it later dawned on me that we could get the best of both worlds by deploying both ideas together, albeit slightly modified. The idea is simple: Use a "light-weight" lookup for pre-routing, since we only need to approximate a good home for the task. And we also retain the post-routing push logic to clean up any inaccuracies caused by a condition of "priority mistargeting" caused by the lightweight lookup. Most of the time, the pre-routing should work and yield lower overhead. In the cases where it doesnt, the post-router will bat cleanup. Signed-off-by: NGregory Haskins <ghaskins@novell.com> Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
It doesn't hurt if we allow the current CPU to be included in the search. We will just simply skip it later if the current CPU turns out to be the lowest. We will use this later in the series Signed-off-by: NGregory Haskins <ghaskins@novell.com> Signed-off-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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