From: Peter Zijlstra <peterz@infradead.org>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>, Rik van Riel <riel@surriel.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/4] sched/numa: Do not move imbalanced load purely on the basis of an idle CPU
Date: Fri, 7 Sep 2018 14:44:32 +0200 [thread overview]
Message-ID: <20180907124432.GN24082@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180907123739.GE1719@techsingularity.net>
On Fri, Sep 07, 2018 at 01:37:39PM +0100, Mel Gorman wrote:
> On Fri, Sep 07, 2018 at 01:33:09PM +0200, Peter Zijlstra wrote:
> > > ---
> > > kernel/sched/fair.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > > index d59d3e00a480..d4c289c11012 100644
> > > --- a/kernel/sched/fair.c
> > > +++ b/kernel/sched/fair.c
> > > @@ -1560,7 +1560,7 @@ static bool task_numa_compare(struct task_numa_env *env,
> > > goto unlock;
> > >
> > > if (!cur) {
> > > - if (maymove || imp > env->best_imp)
> > > + if (maymove)
> > > goto assign;
> > > else
> > > goto unlock;
> >
> > Srikar's patch here:
> >
> > http://lkml.kernel.org/r/1533276841-16341-4-git-send-email-srikar@linux.vnet.ibm.com
> >
> > Also frobs this condition, but in a less radical way. Does that yield
> > similar results?
>
> I can check. I do wonder of course if the less radical approach just means
> that automatic NUMA balancing and the load balancer simply disagree about
> placement at a different time. It'll take a few days to have an answer as
> the battery of workloads to check this take ages.
Yeah, I was afraid it would.. Srikar, can you also evaluate, I suspect
we'll have to pick one of these two patches.
next prev parent reply other threads:[~2018-09-07 12:44 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-07 10:11 [PATCH 0/4] Follow-up fixes for v4.19-rc1 NUMA balancing Mel Gorman
2018-09-07 10:11 ` [PATCH 1/4] sched/numa: Remove redundant numa_stats nr_running field Mel Gorman
2018-09-07 10:11 ` [PATCH 2/4] sched/numa: Remove unused calculations in update_numa_stats Mel Gorman
2018-09-07 10:11 ` [PATCH 3/4] sched/numa: Stop comparing tasks for NUMA placement after selecting an idle core Mel Gorman
2018-09-07 13:05 ` Srikar Dronamraju
2018-09-07 14:20 ` Mel Gorman
2018-09-07 10:11 ` [PATCH 4/4] sched/numa: Do not move imbalanced load purely on the basis of an idle CPU Mel Gorman
2018-09-07 11:33 ` Peter Zijlstra
2018-09-07 12:37 ` Mel Gorman
2018-09-07 12:44 ` Peter Zijlstra [this message]
2018-09-07 13:42 ` Srikar Dronamraju
2018-09-07 14:28 ` Mel Gorman
2018-09-10 9:41 ` Mel Gorman
2018-09-12 6:54 ` Srikar Dronamraju
2018-09-12 9:36 ` Peter Zijlstra
2018-09-12 10:45 ` Srikar Dronamraju
2018-09-12 9:57 ` Ingo Molnar
2018-09-12 10:27 ` Srikar Dronamraju
2018-09-12 10:57 ` Mel Gorman
2018-09-12 10:52 ` Mel Gorman
2018-09-07 11:24 ` [PATCH 0/4] Follow-up fixes for v4.19-rc1 NUMA balancing Peter Zijlstra
2018-09-07 12:29 ` Mel Gorman
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