From: Valentin Schneider <valentin.schneider@arm.com>
To: "Song Bao Hua \(Barry Song\)" <song.bao.hua@hisilicon.com>,
"vincent.guittot\@linaro.org" <vincent.guittot@linaro.org>,
"mingo\@redhat.com" <mingo@redhat.com>,
"peterz\@infradead.org" <peterz@infradead.org>,
"juri.lelli\@redhat.com" <juri.lelli@redhat.com>,
"dietmar.eggemann\@arm.com" <dietmar.eggemann@arm.com>,
"rostedt\@goodmis.org" <rostedt@goodmis.org>,
"bsegall\@google.com" <bsegall@google.com>,
"mgorman\@suse.de" <mgorman@suse.de>
Cc: "linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linuxarm\@openeuler.org" <linuxarm@openeuler.org>
Subject: RE: [PATCH] sched/topology: remove redundant cpumask_and in init_overlap_sched_group
Date: Sun, 07 Mar 2021 18:19:43 +0000 [thread overview]
Message-ID: <jhj8s6y7rnk.mognet@arm.com> (raw)
In-Reply-To: <27e60cb105e040deb16af774399db15e@hisilicon.com>
On 05/03/21 20:25, Song Bao Hua (Barry Song) wrote:
>> -----Original Message-----
>> From: Valentin Schneider [mailto:valentin.schneider@arm.com]
>> Sent: Saturday, March 6, 2021 12:49 AM
>> To: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>;
>> vincent.guittot@linaro.org; mingo@redhat.com; peterz@infradead.org;
>> juri.lelli@redhat.com; dietmar.eggemann@arm.com; rostedt@goodmis.org;
>> bsegall@google.com; mgorman@suse.de
>> Cc: linux-kernel@vger.kernel.org; linuxarm@openeuler.org; Song Bao Hua (Barry
>> Song) <song.bao.hua@hisilicon.com>
>> Subject: Re: [PATCH] sched/topology: remove redundant cpumask_and in
>> init_overlap_sched_group
>>
>> On 05/03/21 11:29, Barry Song wrote:
>> > mask is built in build_balance_mask() by for_each_cpu(i, sg_span), so
>> > it must be a subset of sched_group_span(sg).
>>
>> So we should indeed have
>>
>> cpumask_subset(sched_group_span(sg), mask)
>>
>> but that doesn't imply
>>
>> cpumask_first(sched_group_span(sg)) == cpumask_first(mask)
>>
>> does it? I'm thinking if in your topology of N CPUs, CPUs 0 and N-1 are the
>> furthest away, you will most likely hit
>
> It is true:
> cpumask_first(sched_group_span(sg)) != cpumask_first(mask)
>
> but
>
> cpumask_first_and(sched_group_span(sg), mask) = cpumask_first(mask)
>
> since mask is always subset of sched_group_span(sg).
>
You're right, I read it the wrong way around, sorry about that.
Reviewed-by: Valentin Schneider <Valentin.Schneider@arm.com>
prev parent reply other threads:[~2021-03-07 18:20 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-04 22:29 [PATCH] sched/topology: remove redundant cpumask_and in init_overlap_sched_group Barry Song
2021-03-05 11:48 ` Valentin Schneider
2021-03-05 20:25 ` Song Bao Hua (Barry Song)
2021-03-07 18:19 ` Valentin Schneider [this message]
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=jhj8s6y7rnk.mognet@arm.com \
--to=valentin.schneider@arm.com \
--cc=bsegall@google.com \
--cc=dietmar.eggemann@arm.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxarm@openeuler.org \
--cc=mgorman@suse.de \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=song.bao.hua@hisilicon.com \
--cc=vincent.guittot@linaro.org \
/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