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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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2586af1ac1
The RT_RUNTIME_SHARE sched feature enables the sharing of rt_runtime between CPUs, allowing a CPU to run a real-time task up to 100% of the time while leaving more space for non-real-time tasks to run on the CPU that lend rt_runtime. The problem is that a CPU can easily borrow enough rt_runtime to allow a spinning rt-task to run forever, starving per-cpu tasks like kworkers, which are non-real-time by design. This patch disables RT_RUNTIME_SHARE by default, avoiding this problem. The feature will still be present for users that want to enable it, though. Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Wei Wang <wvw@google.com> Link: https://lkml.kernel.org/r/b776ab46817e3db5d8ef79175fa0d71073c051c7.1600697903.git.bristot@redhat.com
92 lines
2.4 KiB
C
92 lines
2.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Only give sleepers 50% of their service deficit. This allows
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* them to run sooner, but does not allow tons of sleepers to
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* rip the spread apart.
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*/
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SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true)
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/*
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* Place new tasks ahead so that they do not starve already running
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* tasks
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*/
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SCHED_FEAT(START_DEBIT, true)
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/*
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* Prefer to schedule the task we woke last (assuming it failed
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* wakeup-preemption), since its likely going to consume data we
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* touched, increases cache locality.
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*/
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SCHED_FEAT(NEXT_BUDDY, false)
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/*
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* Prefer to schedule the task that ran last (when we did
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* wake-preempt) as that likely will touch the same data, increases
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* cache locality.
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*/
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SCHED_FEAT(LAST_BUDDY, true)
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/*
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* Consider buddies to be cache hot, decreases the likelyness of a
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* cache buddy being migrated away, increases cache locality.
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*/
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SCHED_FEAT(CACHE_HOT_BUDDY, true)
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/*
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* Allow wakeup-time preemption of the current task:
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*/
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SCHED_FEAT(WAKEUP_PREEMPTION, true)
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SCHED_FEAT(HRTICK, false)
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SCHED_FEAT(DOUBLE_TICK, false)
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/*
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* Decrement CPU capacity based on time not spent running tasks
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*/
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SCHED_FEAT(NONTASK_CAPACITY, true)
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/*
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* Queue remote wakeups on the target CPU and process them
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* using the scheduler IPI. Reduces rq->lock contention/bounces.
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*/
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SCHED_FEAT(TTWU_QUEUE, true)
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/*
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* When doing wakeups, attempt to limit superfluous scans of the LLC domain.
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*/
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SCHED_FEAT(SIS_AVG_CPU, false)
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SCHED_FEAT(SIS_PROP, true)
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/*
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* Issue a WARN when we do multiple update_rq_clock() calls
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* in a single rq->lock section. Default disabled because the
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* annotations are not complete.
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*/
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SCHED_FEAT(WARN_DOUBLE_CLOCK, false)
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#ifdef HAVE_RT_PUSH_IPI
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/*
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* In order to avoid a thundering herd attack of CPUs that are
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* lowering their priorities at the same time, and there being
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* a single CPU that has an RT task that can migrate and is waiting
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* to run, where the other CPUs will try to take that CPUs
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* rq lock and possibly create a large contention, sending an
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* IPI to that CPU and let that CPU push the RT task to where
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* it should go may be a better scenario.
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*/
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SCHED_FEAT(RT_PUSH_IPI, true)
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#endif
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SCHED_FEAT(RT_RUNTIME_SHARE, false)
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SCHED_FEAT(LB_MIN, false)
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SCHED_FEAT(ATTACH_AGE_LOAD, true)
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SCHED_FEAT(WA_IDLE, true)
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SCHED_FEAT(WA_WEIGHT, true)
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SCHED_FEAT(WA_BIAS, true)
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/*
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* UtilEstimation. Use estimated CPU utilization.
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*/
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SCHED_FEAT(UTIL_EST, true)
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SCHED_FEAT(UTIL_EST_FASTUP, true)
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