From: Peter Zijlstra <peterz@infradead.org>
To: Mike Galbraith <efault@gmx.de>
Cc: mingo@kernel.org, vincent.guittot@linaro.org,
linux-kernel@vger.kernel.org, juri.lelli@redhat.com,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
corbet@lwn.net, qyousef@layalina.io, chris.hyser@oracle.com,
patrick.bellasi@matbug.net, pjt@google.com, pavel@ucw.cz,
qperret@google.com, tim.c.chen@linux.intel.com,
joshdon@google.com, timj@gnu.org, kprateek.nayak@amd.com,
yu.c.chen@intel.com, youssefesmat@chromium.org,
joel@joelfernandes.org
Subject: Re: [PATCH 10/10] sched/fair: Implement an EEVDF like policy
Date: Thu, 9 Mar 2023 16:39:05 +0100 [thread overview]
Message-ID: <ZAn9mfs0qgPtBr0r@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <ZAn7QAjQvw5q6aI5@hirez.programming.kicks-ass.net>
On Thu, Mar 09, 2023 at 04:29:04PM +0100, Peter Zijlstra wrote:
> On Thu, Mar 09, 2023 at 01:44:13PM +0100, Peter Zijlstra wrote:
> > On Thu, Mar 09, 2023 at 10:06:33AM +0100, Peter Zijlstra wrote:
> > > Hi Mike!
> > >
> > > On Wed, Mar 08, 2023 at 02:36:01PM +0100, Mike Galbraith wrote:
> > > > On Wed, 2023-03-08 at 09:39 +0100, Mike Galbraith wrote:
> > > > >
> > > > > Curiosity got the best of me...
> > > >
> > > > Remember this little bugger, allegedly distilled from a real
> > > > application control thread starvation issue?
> > >
> > > Oooh, yeah, I should still have that somewhere. I'll try and remember
> > > what exactly was needed to make it behave properly.
> >
> > That thing wants both wakeup preemption and sleeper bonus. Specifically,
> > it needs the signal to insta-preempt the 'pointless' kill loop.
> >
> > What happens is that while positive lag, we get this, when negative lag
> > happens wakeup-preemption is not achieved and we get delayed by a full
> > tick.
> >
> > This gets us very little actual runtime.
> >
> > Let me see what do do about that...
>
> So if I add TICK_NSEC based sleeper bonus (/2 for gentle), then starve
> works -- this is the absolutely minimal amount required. It sucks a bit
> it's HZ dependent, but alas.
>
> Also, the whole sleeper bonus gets us back into needing to track the old
> vruntime and the overflow crap for super long sleeps and all that fugly
> :/ I was so hoping we could delete that code.
>
> Oh well.
>
> (also, did you know that removing the debug cruft helps with running
> numbers? ;-)
Also, it helps to turn the sched_feat on... clearly i should be calling
it a day.
next prev parent reply other threads:[~2023-03-09 15:39 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 13:25 [PATCH 00/10] sched: EEVDF using latency-nice Peter Zijlstra
2023-03-06 13:25 ` [PATCH 01/10] sched: Introduce latency-nice as a per-task attribute Peter Zijlstra
2023-03-06 13:25 ` [PATCH 02/10] sched/core: Propagate parent tasks latency requirements to the child task Peter Zijlstra
2023-03-06 13:25 ` [PATCH 03/10] sched: Allow sched_{get,set}attr to change latency_nice of the task Peter Zijlstra
2023-03-06 13:25 ` [PATCH 04/10] sched/fair: Add latency_offset Peter Zijlstra
2023-03-06 13:25 ` [PATCH 05/10] sched/fair: Add sched group latency support Peter Zijlstra
2023-03-06 13:25 ` [PATCH 06/10] sched/fair: Add avg_vruntime Peter Zijlstra
2023-03-21 13:58 ` Chen Yu
2023-03-21 16:04 ` Peter Zijlstra
2023-03-24 7:12 ` Chen Yu
2023-03-24 10:03 ` Peter Zijlstra
2023-03-06 13:25 ` [PATCH 07/10] sched/fair: Remove START_DEBIT Peter Zijlstra
2023-03-06 13:25 ` [PATCH 08/10] sched/fair: Add lag based placement Peter Zijlstra
2023-03-16 22:49 ` Tim Chen
2023-03-06 13:25 ` [PATCH 09/10] rbtree: Add rb_add_augmented_cached() helper Peter Zijlstra
2023-03-06 13:25 ` [PATCH 10/10] sched/fair: Implement an EEVDF like policy Peter Zijlstra
2023-03-08 8:39 ` Mike Galbraith
2023-03-08 9:26 ` Mike Galbraith
2023-03-08 13:36 ` Mike Galbraith
2023-03-09 4:23 ` Mike Galbraith
2023-03-10 20:38 ` Peter Zijlstra
2023-03-11 5:53 ` Mike Galbraith
2023-03-11 7:56 ` Mike Galbraith
2023-03-09 9:06 ` Peter Zijlstra
2023-03-09 12:44 ` Peter Zijlstra
2023-03-09 15:29 ` Peter Zijlstra
2023-03-09 15:39 ` Peter Zijlstra [this message]
2023-03-09 16:24 ` Mike Galbraith
2023-03-09 16:42 ` Peter Zijlstra
2023-03-07 10:27 ` [PATCH 00/10] sched: EEVDF using latency-nice Vincent Guittot
2023-03-07 13:08 ` Peter Zijlstra
2023-03-08 15:13 ` Shrikanth Hegde
2023-03-22 6:49 ` K Prateek Nayak
2023-03-22 9:38 ` K Prateek Nayak
2023-03-23 11:53 ` Pavel Machek
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