From: Peter Zijlstra <peterz@infradead.org>
To: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
Tejun Heo <tj@kernel.org>,
x86@kernel.org
Subject: Re: [tip: sched/core] sched/fair: Multi-LLC select_idle_sibling()
Date: Mon, 5 Jun 2023 21:07:46 +0200 [thread overview]
Message-ID: <20230605190746.GX83892@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <3051ad44-0ac3-e77b-3178-fac7cac3b3f2@samsung.com>
On Mon, Jun 05, 2023 at 05:25:30PM +0200, Marek Szyprowski wrote:
> nfortunately it causes
> regression on my ARM 64bit Exynos5433-based TM2e test board during the
> CPU hotplug tests.
Can you elucidate an ARM illiterate on the actual topology of that
machine?
> CPU: 6 PID: 43 Comm: cpuhp/6 Not tainted 6.4.0-rc1+ #13640
> Hardware name: Samsung TM2E board (DT)
> pstate: 000000c5 (nzcv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : __bitmap_and+0x4c/0x78
> lr : select_idle_cpu+0x64/0x450
Btw, where is lr at? Is that perhaps per_cpu(sd_llc) being NULL or
something?
> > ---
> > kernel/sched/fair.c | 38 ++++++++++++++++++++++++++++++++++++++
> > kernel/sched/features.h | 1 +
> > 2 files changed, 39 insertions(+)
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 48b6f0c..0172458 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -7028,6 +7028,38 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool
> > }
> >
> > /*
> > + * For the multiple-LLC per node case, make sure to try the other LLC's if the
> > + * local LLC comes up empty.
> > + */
> > +static int
> > +select_idle_node(struct task_struct *p, struct sched_domain *sd, int target)
> > +{
> > + struct sched_domain *parent = sd->parent;
> > + struct sched_group *sg;
> > +
> > + /* Make sure to not cross nodes. */
> > + if (!parent || parent->flags & SD_NUMA)
> > + return -1;
> > +
> > + sg = parent->groups;
> > + do {
> > + int cpu = cpumask_first(sched_group_span(sg));
> > + struct sched_domain *sd_child;
> > +
> > + sd_child = per_cpu(sd_llc, cpu);
IOW, sd_child end up NULL?
> > + if (sd_child != sd) {
> > + int i = select_idle_cpu(p, sd_child, test_idle_cores(cpu), cpu);
> > + if ((unsigned)i < nr_cpumask_bits)
> > + return i;
> > + }
> > +
> > + sg = sg->next;
> > + } while (sg != parent->groups);
> > +
> > + return -1;
> > +}
next prev parent reply other threads:[~2023-06-05 19:08 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-31 12:04 [tip: sched/core] sched/fair: Multi-LLC select_idle_sibling() tip-bot2 for Peter Zijlstra
2023-06-01 3:41 ` Abel Wu
2023-06-01 8:09 ` Peter Zijlstra
2023-06-01 9:33 ` K Prateek Nayak
2023-06-01 11:13 ` Peter Zijlstra
2023-06-01 11:56 ` Peter Zijlstra
2023-06-01 12:00 ` Peter Zijlstra
2023-06-01 14:47 ` Peter Zijlstra
2023-06-01 15:35 ` Peter Zijlstra
2023-06-02 5:13 ` K Prateek Nayak
2023-06-02 6:54 ` Peter Zijlstra
2023-06-02 9:19 ` K Prateek Nayak
2023-06-07 18:32 ` K Prateek Nayak
2023-06-13 8:25 ` Peter Zijlstra
2023-06-13 10:30 ` K Prateek Nayak
2023-06-14 8:17 ` Peter Zijlstra
2023-06-14 14:58 ` Chen Yu
2023-06-14 15:13 ` Peter Zijlstra
2023-06-21 7:16 ` Chen Yu
2023-06-16 6:34 ` K Prateek Nayak
2023-07-05 11:57 ` Peter Zijlstra
2023-07-08 13:17 ` Chen Yu
2023-07-12 17:19 ` Chen Yu
2023-07-13 3:43 ` K Prateek Nayak
2023-07-17 1:09 ` Chen Yu
2023-06-02 7:00 ` Peter Zijlstra
2023-06-01 14:51 ` Peter Zijlstra
2023-06-02 5:17 ` K Prateek Nayak
2023-06-02 9:06 ` Gautham R. Shenoy
2023-06-02 11:23 ` Peter Zijlstra
2023-06-01 16:44 ` Chen Yu
2023-06-02 3:12 ` K Prateek Nayak
[not found] ` <CGME20230605152531eucas1p2a10401ec2180696cc9a5f2e94a67adca@eucas1p2.samsung.com>
2023-06-05 15:25 ` Marek Szyprowski
2023-06-05 17:56 ` Peter Zijlstra
2023-06-05 19:07 ` Peter Zijlstra [this message]
2023-06-05 22:20 ` Marek Szyprowski
2023-06-06 7:58 ` Chen Yu
2023-06-01 8:43 tip-bot2 for Peter Zijlstra
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=20230605190746.GX83892@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-tip-commits@vger.kernel.org \
--cc=m.szyprowski@samsung.com \
--cc=tj@kernel.org \
--cc=x86@kernel.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;
as well as URLs for NNTP newsgroup(s).