From: Vincent Guittot <vincent.guittot@linaro.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Steven Rostedt <rostedt@goodmis.org>,
Qais Yousef <qais.yousef@arm.com>,
Juri Lelli <juri.lelli@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
John Stultz <john.stultz@linaro.org>
Subject: Re: [PATCH 13/23] sched,ion: Convert to sched_set_normal()
Date: Wed, 22 Apr 2020 17:09:15 +0200 [thread overview]
Message-ID: <CAKfTPtDa2JPtc2qPSe=d187u8pp7AdvV4wKJiUJsDiAvUTE9hg@mail.gmail.com> (raw)
In-Reply-To: <20200422135921.GL20730@hirez.programming.kicks-ass.net>
On Wed, 22 Apr 2020 at 15:59, Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Wed, Apr 22, 2020 at 03:36:22PM +0200, Vincent Guittot wrote:
> > On Wed, 22 Apr 2020 at 15:29, Peter Zijlstra <peterz@infradead.org> wrote:
> > >
> > > On Wed, Apr 22, 2020 at 03:21:45PM +0200, Vincent Guittot wrote:
> > > > On Wed, 22 Apr 2020 at 13:29, Peter Zijlstra <peterz@infradead.org> wrote:
> > > > >
> > > > > In an attempt to take away sched_setscheduler() from modules, change
> > > > > this into sched_set_normal(.nice = 19).
> > > > >
> > > > > Cc: john.stultz@linaro.org
> > > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > > > > Reviewed-by: Ingo Molnar <mingo@kernel.org>
> > > > > ---
> > > > > drivers/staging/android/ion/ion_heap.c | 3 ---
> > > > > 1 file changed, 3 deletions(-)
> > > > >
> > > > > --- a/drivers/staging/android/ion/ion_heap.c
> > > > > +++ b/drivers/staging/android/ion/ion_heap.c
> > > > > @@ -244,8 +244,6 @@ static int ion_heap_deferred_free(void *
> > > > >
> > > > > int ion_heap_init_deferred_free(struct ion_heap *heap)
> > > > > {
> > > > > - struct sched_param param = { .sched_priority = 0 };
> > > > > -
> > > > > INIT_LIST_HEAD(&heap->free_list);
> > > > > init_waitqueue_head(&heap->waitqueue);
> > > > > heap->task = kthread_run(ion_heap_deferred_free, heap,
> > > > > @@ -255,7 +253,7 @@ int ion_heap_init_deferred_free(struct i
> > > > > __func__);
> > > > > return PTR_ERR_OR_ZERO(heap->task);
> > > > > }
> > > > > - sched_setscheduler(heap->task, SCHED_IDLE, ¶m);
> > > > > + sched_set_normal(heap->task, 19);
> > > >
> > > > Would it make sense to have a sched_set_idle(task) to enable kernel
> > > > setting SCHED_IDLE task ?
> > > >
> > > > SCHED_NORMAL w/ nice 19 and SCHED_IDLE tasks are not treated in the
> > > > same way when checking for preemption at wakeup
> > >
> > > Yeah, but does it really matter? I did indeed consider it, but got
> > > lazy. Is there a definite need for IDLE?
> >
> > John is the best to answer this for this driver but SCHED_IDLE will
> > let other tasks which might be involved in end user interaction like
> > on Android to run first
>
> So I don't much like SCHED_IDLE because it introduces some pretty
> horrible tail latencies. Consider the IDLE task holding a lock, then the
> lock waiter will have to wait until the task gets around to running.
Yes one must be careful when using it
>
> It's not unbounded, like a true idle-time scheduler would be, but it can
> still be pretty horrible. nice19 has some of that too of course, but
> idle has it worse, esp. also because it begs others to preempt it.
Yeah... you have to pay the benefit of letting other tasks to preempt
faster. But both sched_idle and nice19 have the same weight and as a
result they will have the same amount of running time. So I'm not
sure that sched-idle will have bigger problems than nice 19 but may be
more often
>
> I should get back to proxy execution I suppose...
next prev parent reply other threads:[~2020-04-22 15:09 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 11:27 [PATCH 00/23] sched: Remove FIFO priorities from modules Peter Zijlstra
2020-04-22 11:27 ` [PATCH 01/23] sched: Provide sched_set_fifo() Peter Zijlstra
2020-04-22 13:11 ` Paul E. McKenney
2020-04-22 13:26 ` Peter Zijlstra
2020-04-22 15:50 ` Paul E. McKenney
2020-04-22 16:33 ` Steven Rostedt
2020-04-22 16:40 ` Paul E. McKenney
2020-04-22 16:46 ` Steven Rostedt
2020-04-22 17:45 ` Paul E. McKenney
2020-04-22 15:50 ` Paul E. McKenney
2020-04-27 17:04 ` Qais Yousef
2020-04-22 11:27 ` [PATCH 02/23] sched,bL_switcher: Convert to sched_set_fifo*() Peter Zijlstra
2020-04-22 13:27 ` Nicolas Pitre
2020-04-22 11:27 ` [PATCH 03/23] sched,crypto: " Peter Zijlstra
2020-04-22 13:33 ` Herbert Xu
2020-04-22 11:27 ` [PATCH 04/23] sched,acpi_pad: " Peter Zijlstra
2020-04-22 16:45 ` Dietmar Eggemann
2020-04-23 8:46 ` Peter Zijlstra
2020-04-22 11:27 ` [PATCH 05/23] sched,drbd: " Peter Zijlstra
2020-04-23 8:57 ` Peter Zijlstra
2020-04-22 11:27 ` [PATCH 06/23] sched,psci: " Peter Zijlstra
2020-04-22 11:55 ` Valentin Schneider
2020-04-22 14:06 ` Sudeep Holla
2020-04-27 16:35 ` Qais Yousef
2020-04-27 16:58 ` Valentin Schneider
2020-04-22 11:27 ` [PATCH 07/23] sched,msm: " Peter Zijlstra
2020-04-22 11:27 ` [PATCH 08/23] sched,drm/scheduler: " Peter Zijlstra
2020-04-22 11:27 ` [PATCH 09/23] sched,ivtv: " Peter Zijlstra
2020-04-22 12:53 ` Steven Rostedt
2020-04-22 13:26 ` Peter Zijlstra
2020-04-24 9:58 ` Hans Verkuil
2020-04-22 11:27 ` [PATCH 10/23] sched,mmc: " Peter Zijlstra
2020-04-22 16:59 ` Ulf Hansson
2020-04-23 8:59 ` Peter Zijlstra
2020-04-23 12:01 ` Ulf Hansson
2020-04-22 11:27 ` [PATCH 11/23] sched,spi: " Peter Zijlstra
2020-04-22 13:56 ` Mark Brown
2020-04-22 14:35 ` Doug Anderson
2020-04-22 15:47 ` Guenter Roeck
2020-04-22 16:41 ` Doug Anderson
2020-04-22 20:16 ` Guenter Roeck
2020-04-22 11:27 ` [PATCH 12/23] sched,powercap: " Peter Zijlstra
2020-04-22 11:27 ` [PATCH 13/23] sched,ion: Convert to sched_set_normal() Peter Zijlstra
2020-04-22 13:21 ` Vincent Guittot
2020-04-22 13:29 ` Peter Zijlstra
2020-04-22 13:36 ` Vincent Guittot
2020-04-22 13:59 ` Peter Zijlstra
2020-04-22 15:09 ` Vincent Guittot [this message]
2020-04-22 15:39 ` Peter Zijlstra
2020-04-22 15:52 ` Vincent Guittot
2020-04-22 15:38 ` Juri Lelli
2020-04-22 15:42 ` Peter Zijlstra
2020-04-22 11:27 ` [PATCH 14/23] sched,powerclamp: Convert to sched_set_fifo() Peter Zijlstra
2020-04-22 11:27 ` [PATCH 15/23] sched,serial: " Peter Zijlstra
2020-04-22 11:27 ` [PATCH 16/23] sched,watchdog: " Peter Zijlstra
2020-04-22 12:51 ` Steven Rostedt
2020-04-22 13:24 ` Peter Zijlstra
2020-04-22 11:27 ` [PATCH 17/23] sched,irq: " Peter Zijlstra
2020-04-22 11:39 ` Peter Zijlstra
2020-04-22 11:27 ` [PATCH 18/23] sched,locktorture: " Peter Zijlstra
2020-04-22 15:51 ` Paul E. McKenney
2020-04-22 11:27 ` [PATCH 19/23] sched,rcuperf: Convert to sched_set_fifo_low() Peter Zijlstra
2020-04-22 15:51 ` Paul E. McKenney
2020-04-22 11:27 ` [PATCH 20/23] sched,rcutorture: " Peter Zijlstra
2020-04-22 15:51 ` Paul E. McKenney
2020-04-22 11:27 ` [PATCH 21/23] sched,psi: " Peter Zijlstra
2020-04-22 15:22 ` Johannes Weiner
2020-04-22 11:27 ` [PATCH 22/23] sched: Remove sched_setscheduler*() EXPORTs Peter Zijlstra
2020-04-22 11:27 ` [PATCH 23/23] sched: Remove sched_set_*() return value Peter Zijlstra
2020-04-22 14:25 ` Ingo Molnar
2020-04-22 16:16 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAKfTPtDa2JPtc2qPSe=d187u8pp7AdvV4wKJiUJsDiAvUTE9hg@mail.gmail.com' \
--to=vincent.guittot@linaro.org \
--cc=bsegall@google.com \
--cc=dietmar.eggemann@arm.com \
--cc=john.stultz@linaro.org \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mgorman@suse.de \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=qais.yousef@arm.com \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).