- 09 12月, 2009 1 次提交
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由 Thomas Gleixner 提交于
sched_rr_get_param calls task->sched_class->get_rr_interval(task) without protection against a concurrent sched_setscheduler() call which modifies task->sched_class. Serialize the access with task_rq_lock(task) and hand the rq pointer into get_rr_interval() as it's needed at least in the sched_fair implementation. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Acked-by: NPeter Zijlstra <peterz@infradead.org> LKML-Reference: <alpine.LFD.2.00.0912090930120.3089@localhost.localdomain> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 04 11月, 2009 1 次提交
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由 Rusty Russell 提交于
find_lowest_rq() wants to call pick_optimal_cpu() on the intersection of sched_domain_span(sd) and lowest_mask. Rather than doing a cpus_and into a temporary, we can open-code it. This actually makes the code slightly clearer, IMHO. Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Acked-by: NGregory Haskins <ghaskins@novell.com> Cc: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <200911031453.15350.rusty@rustcorp.com.au> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 21 9月, 2009 1 次提交
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由 Peter Williams 提交于
By removing the need for it to know details of scheduling classes. This allows PlugSched to define orthogonal scheduling classes. Signed-off-by: NPeter Williams <pwil3058@bigpond.net.au> Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Cc: Mike Galbraith <efault@gmx.de> LKML-Reference: <06d1b89ee15a0eef82d7.1253496713@mudlark.pw.nest> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 15 9月, 2009 3 次提交
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由 Peter Zijlstra 提交于
In order to extend the functions to have more than 1 flag (sync), rename the argument to flags, and explicitly define a WF_ space for individual flags. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
In order to be able to rename the sync argument, we need to rename the current flag argument. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
Rather ugly patch to fully place the sched_balance_self() code inside the fair class. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 04 9月, 2009 1 次提交
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由 Peter Zijlstra 提交于
Keep an average on the amount of time spend on RT tasks and use that fraction to scale down the cpu_power for regular tasks. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Tested-by: NAndreas Herrmann <andreas.herrmann3@amd.com> Acked-by: NAndreas Herrmann <andreas.herrmann3@amd.com> Acked-by: NGautham R Shenoy <ego@in.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> LKML-Reference: <20090901083826.287778431@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 02 8月, 2009 4 次提交
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由 Ingo Molnar 提交于
This build bug: In file included from kernel/sched.c:1765: kernel/sched_rt.c: In function ‘has_pushable_tasks’: kernel/sched_rt.c:1069: error: ‘struct rt_rq’ has no member named ‘pushable_tasks’ kernel/sched_rt.c: In function ‘pick_next_task_rt’: kernel/sched_rt.c:1084: error: ‘struct rq’ has no member named ‘post_schedule’ Triggers because both pushable_tasks and post_schedule are SMP-only fields. Move pushable_tasks() to the SMP section and #ifdef the post_schedule use. Cc: Gregory Haskins <ghaskins@novell.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20090729150422.17691.55590.stgit@dev.haskins.net> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Peter Zijlstra 提交于
A frequent mistake appears to be to call task_of() on a scheduler entity that is not actually a task, which can result in a wild pointer. Add a check to catch these mistakes. Suggested-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
Reflect "active" cpus in the rq->rd->online field, instead of the online_map. The motivation is that things that use the root-domain code (such as cpupri) only care about cpus classified as "active" anyway. By synchronizing the root-domain state with the active map, we allow several optimizations. For instance, we can remove an extra cpumask_and from the scheduler hotpath by utilizing rq->rd->online (since it is now a cached version of cpu_active_map & rq->rd->span). Signed-off-by: NGregory Haskins <ghaskins@novell.com> Acked-by: NPeter Zijlstra <peterz@infradead.org> Acked-by: NMax Krasnyansky <maxk@qualcomm.com> Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20090730145723.25226.24493.stgit@dev.haskins.net> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Gregory Haskins 提交于
We currently have an explicit "needs_post" vtable method which returns a stack variable for whether we should later run post-schedule. This leads to an awkward exchange of the variable as it bubbles back up out of the context switch. Peter Zijlstra observed that this information could be stored in the run-queue itself instead of handled on the stack. Therefore, we revert to the method of having context_switch return void, and update an internal rq->post_schedule variable when we require further processing. In addition, we fix a race condition where we try to access current->sched_class without holding the rq->lock. This is technically racy, as the sched-class could change out from under us. Instead, we reference the per-rq post_schedule variable with the runqueue unlocked, but with preemption disabled to see if we need to reacquire the rq->lock. Finally, we clean the code up slightly by removing the #ifdef CONFIG_SMP conditionals from the schedule() call, and implement some inline helper functions instead. This patch passes checkpatch, and rt-migrate. Signed-off-by: NGregory Haskins <ghaskins@novell.com> Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <20090729150422.17691.55590.stgit@dev.haskins.net> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 10 7月, 2009 1 次提交
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由 Peter Zijlstra 提交于
Fixes an easily triggerable BUG() when setting process affinities. Make sure to count the number of migratable tasks in the same place: the root rt_rq. Otherwise the number doesn't make sense and we'll hit the BUG in set_cpus_allowed_rt(). Also, make sure we only count tasks, not groups (this is probably already taken care of by the fact that rt_se->nr_cpus_allowed will be 0 for groups, but be more explicit) Tested-by: NThomas Gleixner <tglx@linutronix.de> CC: stable@kernel.org Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: NGregory Haskins <ghaskins@novell.com> LKML-Reference: <1247067476.9777.57.camel@twins> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 09 6月, 2009 1 次提交
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由 Yinghai Lu 提交于
These are defined as static cpumask_var_t so if MAXSMP is not used, they are cleared already. Avoid surprises when MAXSMP is enabled. Signed-off-by: NYinghai Lu <yinghai.lu@kernel.org> Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
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- 01 4月, 2009 1 次提交
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由 Rusty Russell 提交于
Impact: cleanup As pointed out by Steven Rostedt. Since the arg in question is unused, we simply change cpupri_find() to accept NULL. Reported-by: NSteven Rostedt <srostedt@redhat.com> Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> LKML-Reference: <200903251501.22664.rusty@rustcorp.com.au> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 01 2月, 2009 1 次提交
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由 Rusty Russell 提交于
cpumask_and() only initializes nr_cpu_ids bits, so the (deprecated) first_cpu() might find one of those uninitialized bits if nr_cpu_ids is less than NR_CPUS (as it can be for CONFIG_CPUMASK_OFFSTACK). Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 16 1月, 2009 1 次提交
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由 Peter Zijlstra 提交于
Ingo Molnar wrote: > here's a new build failure with tip/sched/rt: > > LD .tmp_vmlinux1 > kernel/built-in.o: In function `set_curr_task_rt': > sched.c:(.text+0x3675): undefined reference to `plist_del' > kernel/built-in.o: In function `pick_next_task_rt': > sched.c:(.text+0x37ce): undefined reference to `plist_del' > kernel/built-in.o: In function `enqueue_pushable_task': > sched.c:(.text+0x381c): undefined reference to `plist_del' Eliminate the plist library kconfig and make it available unconditionally. Signed-off-by: NPeter Zijlstra <peterz@infradead.org> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 14 1月, 2009 2 次提交
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由 Gregory Haskins 提交于
Ingo found a build error in the scheduler when RT_GROUP_SCHED was enabled, but SMP was not. This patch rearranges the code such that it is a little more streamlined and compiles under all permutations of SMP, UP and RT_GROUP_SCHED. It was boot tested on my 4-way x86_64 and it still passes preempt-test. Signed-off-by: NGregory Haskins <ghaskins@novell.com>
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由 Gregory Haskins 提交于
Signed-off-by: NGregory Haskins <ghaskins@novell.com>
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- 12 1月, 2009 1 次提交
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由 Mike Travis 提交于
Impact: reduce stack usage, cleanup Use a cpumask_var_t in find_lowest_rq() and clean up other old cpumask_t calls. Signed-off-by: NMike Travis <travis@sgi.com>
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- 04 1月, 2009 1 次提交
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由 Mike Travis 提交于
Impact: prevents panic from stack overflow on numa-capable machines. Some of the "removal of stack hogs" changes in kernel/sched.c by using node_to_cpumask_ptr were undone by the early cpumask API updates, and causes a panic due to stack overflow. This patch undoes those changes by using cpumask_of_node() which returns a 'const struct cpumask *'. In addition, cpu_coregoup_map is replaced with cpu_coregroup_mask further reducing stack usage. (Both of these updates removed 9 FIXME's!) Also: Pick up some remaining changes from the old 'cpumask_t' functions to the new 'struct cpumask *' functions. Optimize memory traffic by allocating each percpu local_cpu_mask on the same node as the referring cpu. Signed-off-by: NMike Travis <travis@sgi.com> Acked-by: NRusty Russell <rusty@rustcorp.com.au> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 29 12月, 2008 8 次提交
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由 Gregory Haskins 提交于
A panic was discovered by Chirag Jog where a BUG_ON sanity check in the new "pushable_task" logic would trigger a panic under certain circumstances: http://lkml.org/lkml/2008/9/25/189 Gilles Carry discovered that the root cause was attributed to the pushable_tasks list getting corrupted in the push_rt_task logic. This was the result of a dropped rq lock in double_lock_balance allowing a task in the process of being pushed to potentially migrate away, and thus corrupt the pushable_tasks() list. I traced back the problem as introduced by the pushable_tasks patch that went in recently. There is a "retry" path in push_rt_task() that actually had a compound conditional to decide whether to retry or exit. I missed the meaning behind the rationale for the virtual "if(!task) goto out;" portion of the compound statement and thus did not handle it properly. The new pushable_tasks logic actually creates three distinct conditions: 1) an untouched and unpushable task should be dequeued 2) a migrated task where more pushable tasks remain should be retried 3) a migrated task where no more pushable tasks exist should exit The original logic mushed (1) and (3) together, resulting in the system dequeuing a migrated task (against an unlocked foreign run-queue nonetheless). To fix this, we get rid of the notion of "paranoid" and we support the three unique conditions properly. The paranoid feature is no longer relevant with the new pushable logic (since pushable naturally limits the loop) anyway, so lets just remove it. Reported-By: NChirag Jog <chirag@linux.vnet.ibm.com> Found-by: NGilles Carry <gilles.carry@bull.net> Signed-off-by: NGregory Haskins <ghaskins@novell.com>
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由 Gregory Haskins 提交于
The RT scheduler employs a "push/pull" design to actively balance tasks within the system (on a per disjoint cpuset basis). When a task is awoken, it is immediately determined if there are any lower priority cpus which should be preempted. This is opposed to the way normal SCHED_OTHER tasks behave, which will wait for a periodic rebalancing operation to occur before spreading out load. When a particular RQ has more than 1 active RT task, it is said to be in an "overloaded" state. Once this occurs, the system enters the active balancing mode, where it will try to push the task away, or persuade a different cpu to pull it over. The system will stay in this state until the system falls back below the <= 1 queued RT task per RQ. However, the current implementation suffers from a limitation in the push logic. Once overloaded, all tasks (other than current) on the RQ are analyzed on every push operation, even if it was previously unpushable (due to affinity, etc). Whats more, the operation stops at the first task that is unpushable and will not look at items lower in the queue. This causes two problems: 1) We can have the same tasks analyzed over and over again during each push, which extends out the fast path in the scheduler for no gain. Consider a RQ that has dozens of tasks that are bound to a core. Each one of those tasks will be encountered and skipped for each push operation while they are queued. 2) There may be lower-priority tasks under the unpushable task that could have been successfully pushed, but will never be considered until either the unpushable task is cleared, or a pull operation succeeds. The net result is a potential latency source for mid priority tasks. This patch aims to rectify these two conditions by introducing a new priority sorted list: "pushable_tasks". A task is added to the list each time a task is activated or preempted. It is removed from the list any time it is deactivated, made current, or fails to push. This works because a task only needs to be attempted to push once. After an initial failure to push, the other cpus will eventually try to pull the task when the conditions are proper. This also solves the problem that we don't completely analyze all tasks due to encountering an unpushable tasks. Now every task will have a push attempted (when appropriate). This reduces latency both by shorting the critical section of the rq->lock for certain workloads, and by making sure the algorithm considers all eligible tasks in the system. [ rostedt: added a couple more BUG_ONs ] Signed-off-by: NGregory Haskins <ghaskins@novell.com> Acked-by: NSteven Rostedt <srostedt@redhat.com>
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由 Gregory Haskins 提交于
We currently run class->post_schedule() outside of the rq->lock, which means that we need to test for the need to post_schedule outside of the lock to avoid a forced reacquistion. This is currently not a problem as we only look at rq->rt.overloaded. However, we want to enhance this going forward to look at more state to reduce the need to post_schedule to a bare minimum set. Therefore, we introduce a new member-func called needs_post_schedule() which tests for the post_schedule condtion without actually performing the work. Therefore it is safe to call this function before the rq->lock is released, because we are guaranteed not to drop the lock at an intermediate point (such as what post_schedule() may do). We will use this later in the series [ rostedt: removed paranoid BUG_ON ] Signed-off-by: NGregory Haskins <ghaskins@novell.com>
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由 Gregory Haskins 提交于
There is no sense in wasting time trying to push a task away that cannot move anywhere else. We gain no benefit from trying to push other tasks at this point, so if the task being woken up is non migratable, just skip the whole operation. This reduces overhead in the wakeup path for certain tasks. Signed-off-by: NGregory Haskins <ghaskins@novell.com>
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由 Gregory Haskins 提交于
We currently take the rq->lock for every cpu in an overload state during pull_rt_tasks(). However, we now have enough information via the highest_prio.[curr|next] fields to determine if there is any tasks of interest to warrant the overhead of the rq->lock, before we actually take it. So we use this information to reduce lock contention during the pull for the case where the source-rq doesnt have tasks that preempt the current task. Signed-off-by: NGregory Haskins <ghaskins@novell.com>
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由 Gregory Haskins 提交于
highest_prio.curr is actually a more accurate way to keep track of the pull_rt_task() threshold since it is always up to date, even if the "next" task migrates during double_lock. Therefore, stop looking at the "next" task object and simply use the highest_prio.curr. Signed-off-by: NGregory Haskins <ghaskins@novell.com>
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由 Gregory Haskins 提交于
We will use this later in the series to reduce the amount of rq-lock contention during a pull operation Signed-off-by: NGregory Haskins <ghaskins@novell.com>
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由 Gregory Haskins 提交于
Move some common definitions up to the function prologe to simplify the body logic. Signed-off-by: NGregory Haskins <ghaskins@novell.com>
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- 17 12月, 2008 1 次提交
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由 Bharata B Rao 提交于
Impact: fix potential of rare crash for_each_leaf_rt_rq() walks an RCU protected list (rq->leaf_rt_rq_list), but doesn't use list_for_each_entry_rcu(). Fix this. Signed-off-by: NBharata B Rao <bharata@linux.vnet.ibm.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 29 11月, 2008 1 次提交
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由 Alexey Dobriyan 提交于
Move double_lock_balance()/double_unlock_balance() higher to fix the following with gcc-3.4.6: CC kernel/sched.o In file included from kernel/sched.c:1605: kernel/sched_rt.c: In function `find_lock_lowest_rq': kernel/sched_rt.c:914: sorry, unimplemented: inlining failed in call to 'double_unlock_balance': function body not available kernel/sched_rt.c:1077: sorry, unimplemented: called from here make[2]: *** [kernel/sched.o] Error 1 Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 26 11月, 2008 1 次提交
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由 Rusty Russell 提交于
Impact: build fix for !CONFIG_SMP Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Acked-by: NMike Travis <travis@sgi.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 25 11月, 2008 5 次提交
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由 Rusty Russell 提交于
Impact: Trivial API conversion NR_CPUS -> nr_cpu_ids cpumask_t -> struct cpumask sizeof(cpumask_t) -> cpumask_size() cpumask_a = cpumask_b -> cpumask_copy(&cpumask_a, &cpumask_b) cpu_set() -> cpumask_set_cpu() first_cpu() -> cpumask_first() cpumask_of_cpu() -> cpumask_of() cpus_* -> cpumask_* There are some FIXMEs where we all archs to complete infrastructure (patches have been sent): cpu_coregroup_map -> cpu_coregroup_mask node_to_cpumask* -> cpumask_of_node There is also one FIXME where we pass an array of cpumasks to partition_sched_domains(): this implies knowing the definition of 'struct cpumask' and the size of a cpumask. This will be fixed in a future patch. Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Rusty Russell 提交于
Impact: (future) size reduction for large NR_CPUS. Dynamically allocating cpumasks (when CONFIG_CPUMASK_OFFSTACK) saves space for small nr_cpu_ids but big CONFIG_NR_CPUS. cpumask_var_t is just a struct cpumask for !CONFIG_CPUMASK_OFFSTACK. Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Rusty Russell 提交于
Impact: stack reduction for large NR_CPUS Dynamically allocating cpumasks (when CONFIG_CPUMASK_OFFSTACK) saves stack space. We simply return if the allocation fails: since we don't use it we could just pass NULL to cpupri_find and have it handle that. Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Rusty Russell 提交于
Impact: (future) size reduction for large NR_CPUS. Dynamically allocating cpumasks (when CONFIG_CPUMASK_OFFSTACK) saves space for small nr_cpu_ids but big CONFIG_NR_CPUS. cpumask_var_t is just a struct cpumask for !CONFIG_CPUMASK_OFFSTACK. def_root_domain is static, and so its masks are initialized with alloc_bootmem_cpumask_var. After that, alloc_cpumask_var is used. Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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由 Rusty Russell 提交于
Impact: trivial wrap of member accesses This eases the transition in the next patch. We also get rid of a temporary cpumask in find_idlest_cpu() thanks to for_each_cpu_and, and sched_balance_self() due to getting weight before setting sd to NULL. Signed-off-by: NRusty Russell <rusty@rustcorp.com.au> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 07 11月, 2008 1 次提交
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由 Sripathi Kodi 提交于
We have a test case which measures the variation in the amount of time needed to perform a fixed amount of work on the preempt_rt kernel. We started seeing deterioration in it's performance recently. The test should never take more than 10 microseconds, but we started 5-10% failure rate. Using elimination method, we traced the problem to commit 1b12bbc7 (lockdep: re-annotate scheduler runqueues). When LOCKDEP is disabled, this patch only adds an additional function call to double_unlock_balance(). Hence I inlined double_unlock_balance() and the problem went away. Here is a patch to make this change. Signed-off-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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- 03 11月, 2008 1 次提交
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由 Dimitri Sivanich 提交于
Impact: micro-optimization to SCHED_FIFO/RR scheduling A very minor improvement, but might it be better to check sched_rt_runtime(rt_rq) before taking the rt_runtime_lock? Peter Zijlstra observes: > Yes, I think its ok to do so. > > Like pointed out in the other thread, there are two races: > > - sched_rt_runtime() going to RUNTIME_INF, and that will be handled > properly by sched_rt_runtime_exceeded() > > - sched_rt_runtime() going to !RUNTIME_INF, and here we can miss an > accounting cycle, but I don't think that is something to worry too > much about. Signed-off-by: NDimitri Sivanich <sivanich@sgi.com> Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NIngo Molnar <mingo@elte.hu> -- kernel/sched_rt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
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- 22 10月, 2008 1 次提交
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由 Li Zefan 提交于
a patch from Henrik Austad did this: >> Do not declare select_task_rq as part of sched_class when CONFIG_SMP is >> not set. Peter observed: > While a proper cleanup, could you do it by re-arranging the methods so > as to not create an additional ifdef? Do not declare select_task_rq and some other methods as part of sched_class when CONFIG_SMP is not set. Also gather those methods to avoid CONFIG_SMP mess. Idea-by: NHenrik Austad <henrik.austad@gmail.com> Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com> Acked-by: NPeter Zijlstra <peterz@infradead.org> Acked-by: NHenrik Austad <henrik@austad.us> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 04 10月, 2008 1 次提交
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由 Dario Faggioli 提交于
While working on the new version of the code for SCHED_SPORADIC I noticed something strange in the present throttling mechanism. More specifically in the throttling timer handler in sched_rt.c (do_sched_rt_period_timer()) and in rt_rq_enqueue(). The problem is that, when unthrottling a runqueue, rt_rq_enqueue() only asks for rescheduling if the runqueue has a sched_entity associated to it (i.e., rt_rq->rt_se != NULL). Now, if the runqueue is the root rq (which has a rt_se = NULL) rescheduling does not take place, and it is delayed to some undefined instant in the future. This imply some random bandwidth usage by the RT tasks under throttling. For instance, setting rt_runtime_us/rt_period_us = 950ms/1000ms an RT task will get less than 95%. In our tests we got something varying between 70% to 95%. Using smaller time values, e.g., 95ms/100ms, things are even worse, and I can see values also going down to 20-25%!! The tests we performed are simply running 'yes' as a SCHED_FIFO task, and checking the CPU usage with top, but we can investigate thoroughly if you think it is needed. Things go much better, for us, with the attached patch... Don't know if it is the best approach, but it solved the issue for us. Signed-off-by: NDario Faggioli <raistlin@linux.it> Signed-off-by: NMichael Trimarchi <trimarchimichael@yahoo.it> Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Cc: <stable@kernel.org> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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