From: Mike Galbraith <efault@gmx.de>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Valentin Schneider <valentin.schneider@arm.com>,
Aubrey Li <aubrey.li@linux.intel.com>,
Barry Song <song.bao.hua@hisilicon.com>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] sched/fair: Couple wakee flips with heavy wakers
Date: Tue, 26 Oct 2021 12:41:36 +0200 [thread overview]
Message-ID: <b53de0da7c863ec4c883a92b2526a0f9132a24cb.camel@gmx.de> (raw)
In-Reply-To: <4105fd08f84c60698b38efcb4d22e999de187d6e.camel@gmx.de>
On Tue, 2021-10-26 at 12:15 +0200, Mike Galbraith wrote:
>
...
Well now, that interruption didn't go as planned. The briefer edit
would have been preferred, but you get the drift, so moving on...
> > > It benefiting NUMA box
> > > hackbench is a valid indicator, but one that is IMO too disconnected
> > > from the real world to carry much weight.
> > >
> >
> > I think if it's not shown to be harmful to a realistic workload but helps
> > an overloaded example then it should be ok. While excessive overload is
> > rare in a realistic workload, it does happen. There are a few workloads
> > I've seen bugs for that were triggered when an excessive number of worker
> > threads get spawned and compete for CPU access which in turns leads more
> > worker threads get spawned. There are application workarounds for this
> > corner case but it still triggers bugs.
>
wake_wide()'s proper test environment is NUMA, not a desktop box, so
patchlet has yet to meet a real world load that qualifies as such.
That it could detect the test load doing nutty stuff like waking a
thread pool three times the size of the box is all well and good, but
not the point.
$.02 WRT poor abused hackbench: if it happens to benefit that's fine,
but I don't think it should ever be considered change validation. It's
a useful tool, but the common massive overload use is just nuts IMO.
-Mike
next prev parent reply other threads:[~2021-10-26 10:42 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-21 14:56 [PATCH 0/2] Reduce stacking and overscheduling Mel Gorman
2021-10-21 14:56 ` [PATCH 1/2] sched/fair: Couple wakee flips with heavy wakers Mel Gorman
2021-10-22 10:26 ` Mike Galbraith
2021-10-22 11:05 ` Mel Gorman
2021-10-22 12:00 ` Mike Galbraith
2021-10-25 6:35 ` Mike Galbraith
2021-10-26 8:18 ` Mel Gorman
2021-10-26 10:15 ` Mike Galbraith
2021-10-26 10:41 ` Mike Galbraith [this message]
2021-10-26 11:57 ` Mel Gorman
2021-10-26 12:13 ` Mike Galbraith
2021-10-27 2:09 ` Mike Galbraith
2021-10-27 9:00 ` Mel Gorman
2021-10-27 10:18 ` Mike Galbraith
2021-11-09 11:56 ` Peter Zijlstra
2021-11-09 12:55 ` Mike Galbraith
2021-10-21 14:56 ` [PATCH 2/2] sched/fair: Increase wakeup_gran if current task has not executed the minimum granularity Mel Gorman
2021-10-28 9:48 [PATCH v4 0/2] Reduce stacking and overscheduling Mel Gorman
2021-10-28 9:48 ` [PATCH 1/2] sched/fair: Couple wakee flips with heavy wakers Mel Gorman
2021-10-28 16:19 ` Tao Zhou
2021-10-29 8:42 ` Mel Gorman
2021-11-10 9:53 ` Tao Zhou
2021-11-10 15:40 ` Mike Galbraith
2021-10-29 15:17 ` Vincent Guittot
2021-10-30 3:11 ` Mike Galbraith
2021-10-30 4:12 ` Mike Galbraith
2021-11-01 8:56 ` Mel Gorman
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