From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Xunlei Pang <xlpang@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Juri Lelli <juri.lelli@redhat.com>,
Wetp Zhang <wetp.zy@linux.alibaba.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched/fair: Fix wrong cpu selecting from isolated domain
Date: Mon, 24 Aug 2020 19:08:20 +0530 [thread overview]
Message-ID: <20200824133820.GA31355@linux.vnet.ibm.com> (raw)
In-Reply-To: <1598272219-43040-1-git-send-email-xlpang@linux.alibaba.com>
* Xunlei Pang <xlpang@linux.alibaba.com> [2020-08-24 20:30:19]:
> We've met problems that occasionally tasks with full cpumask
> (e.g. by putting it into a cpuset or setting to full affinity)
> were migrated to our isolated cpus in production environment.
>
> After some analysis, we found that it is due to the current
> select_idle_smt() not considering the sched_domain mask.
>
> Fix it by checking the valid domain mask in select_idle_smt().
>
> Fixes: 10e2f1acd010 ("sched/core: Rewrite and improve select_idle_siblings())
> Reported-by: Wetp Zhang <wetp.zy@linux.alibaba.com>
> Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
> ---
> kernel/sched/fair.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 1a68a05..fa942c4 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6075,7 +6075,7 @@ static int select_idle_core(struct task_struct *p, struct sched_domain *sd, int
> /*
> * Scan the local SMT mask for idle CPUs.
> */
> -static int select_idle_smt(struct task_struct *p, int target)
> +static int select_idle_smt(struct task_struct *p, struct sched_domain *sd, int target)
> {
> int cpu;
>
> @@ -6083,7 +6083,8 @@ static int select_idle_smt(struct task_struct *p, int target)
> return -1;
>
> for_each_cpu(cpu, cpu_smt_mask(target)) {
> - if (!cpumask_test_cpu(cpu, p->cpus_ptr))
> + if (!cpumask_test_cpu(cpu, p->cpus_ptr) ||
> + !cpumask_test_cpu(cpu, sched_domain_span(sd)))
> continue;
Don't think this is right thing to do. What if this task had set a cpumask
that doesn't cover all the cpus in this sched_domain_span(sd)
cpu_smt_mask(target) would already limit to the sched_domain_span(sd) so I
am not sure how this can help?
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2020-08-24 13:40 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-24 12:30 [PATCH] sched/fair: Fix wrong cpu selecting from isolated domain Xunlei Pang
2020-08-24 13:38 ` Srikar Dronamraju [this message]
2020-08-25 2:11 ` xunlei
2020-08-25 2:59 ` Srikar Dronamraju
2020-08-25 6:37 ` Jiang Biao
2020-08-25 9:27 ` xunlei
2020-08-25 12:46 ` Jiang Biao
2020-08-28 2:53 ` Xunlei Pang
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=20200824133820.GA31355@linux.vnet.ibm.com \
--to=srikar@linux.vnet.ibm.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=vincent.guittot@linaro.org \
--cc=wetp.zy@linux.alibaba.com \
--cc=xlpang@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;
as well as URLs for NNTP newsgroup(s).