Messages in this thread | | | Subject | Re: [PATCH] sched/rt: Disable RT_RUNTIME_SHARE by default | From | Daniel Bristot de Oliveira <> | Date | Tue, 22 Sep 2020 21:04:18 +0200 |
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On 9/22/20 7:14 PM, Wei Wang wrote: > On Mon, Sep 21, 2020 at 7:40 AM Daniel Bristot de Oliveira > <bristot@redhat.com> wrote: >> >> 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> >> Cc: Ingo Molnar <mingo@redhat.com> >> Cc: Peter Zijlstra <peterz@infradead.org> >> Cc: Juri Lelli <juri.lelli@redhat.com> >> Cc: Vincent Guittot <vincent.guittot@linaro.org> >> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> >> Cc: Steven Rostedt <rostedt@goodmis.org> >> Cc: Ben Segall <bsegall@google.com> >> Cc: Mel Gorman <mgorman@suse.de> >> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> >> Cc: Thomas Gleixner <tglx@linutronix.de> >> Cc: linux-kernel@vger.kernel.org >> --- >> kernel/sched/features.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/sched/features.h b/kernel/sched/features.h >> index 7481cd96f391..68d369cba9e4 100644 >> --- a/kernel/sched/features.h >> +++ b/kernel/sched/features.h >> @@ -77,7 +77,7 @@ SCHED_FEAT(WARN_DOUBLE_CLOCK, false) >> SCHED_FEAT(RT_PUSH_IPI, true) >> #endif >> >> -SCHED_FEAT(RT_RUNTIME_SHARE, true) >> +SCHED_FEAT(RT_RUNTIME_SHARE, false) >> SCHED_FEAT(LB_MIN, false) >> SCHED_FEAT(ATTACH_AGE_LOAD, true) >> >> -- >> 2.26.2 >> > > Tested on an Android device and can no longer see long running RT > tasks (yes, Android have those for reasons). >
So:
Tested-by: Wei Wang <wvw@google.com>
?
Thanks! -- Daniel
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