From: Mel Gorman <mgorman@suse.de>
To: ????????? <tianchen.dingtianc@alibaba-inc.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
?????? <yun.wang@linux.alibaba.com>
Subject: Re: [RFC PATCH] sched/numa: fix bug in update_task_scan_period
Date: Tue, 11 Aug 2020 12:01:54 +0100 [thread overview]
Message-ID: <20200811110154.GY3510@suse.de> (raw)
In-Reply-To: <44875b14-00ea-4e61-aba7-4809808c4b2a.tianchen.dingtianc@alibaba-inc.com>
On Tue, Aug 11, 2020 at 04:30:31PM +0800, ????????? wrote:
> When p->numa_faults_locality[2] > 0, numa_scan_period is doubled, but
> this array will never be cleared, which causes scanning period always
> reaching its max value. This patch clears numa_faults_locality after
> numa_scan_period being doubled to fix this bug.
>
An out label at the end of the function to clears numa_faults_locality
would also work with a comment explaining why. That aside, what is
the user-visible impact of the patch? If there are no useful faults or
migration failures, it makes sense that scanning is very slow until the
situation changes. The corner case is that a migration failure might keep
the scan rate slower than it should be but the flip side is that fixing
it might increase the scan rate and still incur migration failures which
introduces overhead with no gain.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2020-08-11 11:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-11 8:30 [RFC PATCH] sched/numa: fix bug in update_task_scan_period 丁天琛
2020-08-11 11:01 ` Mel Gorman [this message]
2020-08-12 3:51 ` 丁天琛
2020-08-14 13:15 ` Mel Gorman
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=20200811110154.GY3510@suse.de \
--to=mgorman@suse.de \
--cc=bsegall@google.com \
--cc=dietmar.eggemann@arm.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=tianchen.dingtianc@alibaba-inc.com \
--cc=vincent.guittot@linaro.org \
--cc=yun.wang@linux.alibaba.com \
/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