From: Mel Gorman <mgorman@techsingularity.net>
To: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: torvalds@linux-foundation.org, tglx@linutronix.de,
mingo@kernel.org, hpa@zytor.com, efault@gmx.de,
linux-kernel@vger.kernel.org, matt@codeblueprint.co.uk,
peterz@infradead.org, ggherdovich@suse.cz,
linux-tip-commits@vger.kernel.org, mpe@ellerman.id.au
Subject: Re: [tip:sched/core] sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine()
Date: Wed, 9 May 2018 17:34:10 +0100 [thread overview]
Message-ID: <20180509163410.trju4eyrtslb3sk5@techsingularity.net> (raw)
In-Reply-To: <20180509105814.GA41120@linux.vnet.ibm.com>
On Wed, May 09, 2018 at 03:58:14AM -0700, Srikar Dronamraju wrote:
> In the other scenario, where wake_affine set p->numa_migrate_preferred to a
> bigger value, the task calls numa_migrate_preferred(),
> numa_migrate_preferred could be before p->numa_migrate_preferred. In
> such a case, we should have stopped the task from migration.
> However we overwrite p->numa_migrate_preferred and do the
> task_numa_migrate(). Somehow this doesn't seem to achieve what the
> commit intended.
>
> Or did I misunderstand?
>
Nope, the logic is broken. While it can be "fixed", the end result adds
complexity for very little gain. I believe the right path for the moment
is a revert and retry at a future date.
Thanks.
--
Mel Gorman
SUSE Labs
prev parent reply other threads:[~2018-05-09 16:34 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-13 13:37 [PATCH 0/6] Reduce migrations and conflicts with automatic NUMA balancing v2 Mel Gorman
2018-02-13 13:37 ` [PATCH 1/6] sched/fair: Avoid an unnecessary lookup of current CPU ID during wake_affine Mel Gorman
2018-02-21 10:27 ` [tip:sched/core] " tip-bot for Mel Gorman
2018-02-13 13:37 ` [PATCH 2/6] sched/fair: Defer calculation of prev_eff_load in wake_affine until needed Mel Gorman
2018-02-21 10:28 ` [tip:sched/core] sched/fair: Defer calculation of 'prev_eff_load' in wake_affine_weight() " tip-bot for Mel Gorman
2018-02-13 13:37 ` [PATCH 3/6] sched/fair: Do not migrate on wake_affine_weight if weights are equal Mel Gorman
2018-02-21 10:28 ` [tip:sched/core] sched/fair: Do not migrate on wake_affine_weight() " tip-bot for Mel Gorman
2018-02-13 13:37 ` [PATCH 4/6] sched/fair: Do not migrate due to a sync wakeup on exit Mel Gorman
2018-02-21 10:29 ` [tip:sched/core] " tip-bot for Peter Zijlstra
2018-02-13 13:37 ` [PATCH 5/6] sched/fair: Consider SD_NUMA when selecting the most idle group to schedule on Mel Gorman
2018-02-21 10:29 ` [tip:sched/core] " tip-bot for Mel Gorman
2018-02-13 13:37 ` [PATCH 6/6] sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine Mel Gorman
2018-02-13 14:01 ` Peter Zijlstra
2018-02-13 14:18 ` Mel Gorman
2018-02-13 14:43 ` Peter Zijlstra
2018-02-13 15:00 ` Mel Gorman
2018-02-13 15:10 ` Peter Zijlstra
2018-02-21 10:30 ` [tip:sched/core] sched/numa: Delay retrying placement for automatic NUMA balance after wake_affine() tip-bot for Mel Gorman
2018-05-07 11:06 ` Srikar Dronamraju
2018-05-09 8:41 ` Mel Gorman
2018-05-09 10:58 ` Srikar Dronamraju
2018-05-09 16:34 ` Mel Gorman [this message]
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