From: Joel Fernandes <joelaf@google.com>
To: Doug Anderson <dianders@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: RT_GROUP_SCHED throttling blocks unthrottled RT tasks?
Date: Fri, 5 Nov 2021 19:05:41 -0400 [thread overview]
Message-ID: <CAJWu+oocnt-yF=R=XxNvjj14hwV8hAewz-696DcAzGdr5ys2sQ@mail.gmail.com> (raw)
In-Reply-To: <CAJWu+orNotdFUe0Bc9ooP+1nzajd=7A9WiSWXwtrsLkWi8gFAg@mail.gmail.com>
On Fri, Nov 5, 2021 at 7:04 PM Joel Fernandes <joelaf@google.com> wrote:
>
> On Fri, Nov 5, 2021 at 1:44 PM Doug Anderson <dianders@chromium.org> wrote:
> [..]
> >
> >
> > I tried gathering some tracing. One bit that might (?) be relevant:
> >
> > cros_ec_spi_hig-179 [000] d.h5 1495.305919: sched_waking:
> > comm=kworker/4:2 pid=5232 prio=120 target_cpu=004
> > cros_ec_spi_hig-179 [000] d.h6 1495.305926: sched_wakeup:
> > comm=kworker/4:2 pid=5232 prio=120 target_cpu=004
> > <idle>-0 [001] d.H5 1495.309113: sched_waking:
> > comm=sugov:6 pid=2658 prio=-1 target_cpu=006
> > <idle>-0 [001] d.H6 1495.309119: sched_wakeup:
> > comm=sugov:6 pid=2658 prio=-1 target_cpu=006
> > cros_ec_spi_hig-179 [000] d.h5 1495.309336: sched_waking:
> > comm=sugov:6 pid=2658 prio=-1 target_cpu=006
> > cros_ec_spi_hig-179 [000] d.h6 1495.309341: sched_wakeup:
> > comm=sugov:6 pid=2658 prio=-1 target_cpu=006
> > <idle>-0 [001] d.H5 1495.312137: sched_waking:
> > comm=sugov:6 pid=2658 prio=-1 target_cpu=006
> > <idle>-0 [001] d.H6 1495.312142: sched_wakeup:
> > comm=sugov:6 pid=2658 prio=-1 target_cpu=006
> > cros_ec_spi_hig-179 [000] d.h5 1495.312859: sched_waking:
> > comm=sugov:6 pid=2658 prio=-1 target_cpu=006
> > cros_ec_spi_hig-179 [000] d.h6 1495.312870: sched_wakeup:
> > comm=sugov:6 pid=2658 prio=-1 target_cpu=006
> >
> > My best guess is that there's some bug in the scheduler where it just
> > loops constantly picking an unthrottled RT task but then incorrectly
> > decides that it's throttled and thus doesn't run it.
>
> Thanks for posting this. Tricky bit indeed. I was wondering if the
> issue is here:
> https://elixir.bootlin.com/linux/latest/source/kernel/sched/rt.c#L1031
Errm, I meant Line 1060 in rt.c
https://elixir.bootlin.com/linux/latest/source/kernel/sched/rt.c#L1060
next prev parent reply other threads:[~2021-11-05 23:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-05 17:44 RT_GROUP_SCHED throttling blocks unthrottled RT tasks? Doug Anderson
2021-11-05 23:04 ` Joel Fernandes
2021-11-05 23:05 ` Joel Fernandes [this message]
2021-11-05 23:10 ` Joel Fernandes
2021-11-16 1:13 ` Doug Anderson
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