LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Valentin Schneider <valentin.schneider@arm.com>
To: Frederic Weisbecker <frederic@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>, Tejun Heo <tj@kernel.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Alex Belits <abelits@marvell.com>, Nitesh Lal <nilal@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Nicolas Saenz <nsaenzju@redhat.com>,
	Christoph Lameter <cl@gentwo.de>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Zefan Li <lizefan.x@bytedance.com>,
	cgroups@vger.kernel.org
Subject: Re: [RFC PATCH 6/6] cpuset: Add cpuset.isolation_mask file
Date: Thu, 15 Jul 2021 00:44:08 +0100	[thread overview]
Message-ID: <87o8b4mpfb.mognet@arm.com> (raw)
In-Reply-To: <20210714231338.GA65963@lothringen>

On 15/07/21 01:13, Frederic Weisbecker wrote:
> On Wed, Jul 14, 2021 at 06:52:43PM +0200, Peter Zijlstra wrote:
>>
>> cpusets already has means to create paritions; why are you creating
>> something else?
>
> I was about to answer that the semantics of isolcpus, which reference
> a NULL domain, are different from SD_LOAD_BALANCE implied by
> cpuset.sched_load_balance. But then I realize that SD_LOAD_BALANCE has
> been removed.
>
> How cpuset.sched_load_balance is implemented then? Commit
> e669ac8ab952df2f07dee1e1efbf40647d6de332 ("sched: Remove checks against
> SD_LOAD_BALANCE") advertize that setting cpuset.sched_load_balance to 0
> ends up creating NULL domain but that's not what I get. For example if I
> mount a single cpuset root (no other cpuset mountpoints):
>
> $ mount -t cgroup none ./cpuset -o cpuset
> $ cd cpuset
> $ cat cpuset.cpus
> 0-7
> $ cat cpuset.sched_load_balance
> 1
> $ echo 0 > cpuset.sched_load_balance
> $ ls /sys/kernel/debug/domains/cpu1/
> domain0  domain1
>
> I still get the domains on all CPUs...

Huh. That's on v5.14-rc1 with an automounted cpuset:

$ cat /sys/fs/cgroup/cpuset/cpuset.cpus
0-5
$ cat /sys/fs/cgroup/cpuset/cpuset.sched_load_balance
1

$ ls /sys/kernel/debug/sched/domains/cpu*
/sys/kernel/debug/sched/domains/cpu0:
domain0  domain1

/sys/kernel/debug/sched/domains/cpu1:
domain0  domain1

/sys/kernel/debug/sched/domains/cpu2:
domain0  domain1

/sys/kernel/debug/sched/domains/cpu3:
domain0  domain1

/sys/kernel/debug/sched/domains/cpu4:
domain0  domain1

/sys/kernel/debug/sched/domains/cpu5:
domain0  domain1

$ echo 0 > /sys/fs/cgroup/cpuset/cpuset.sched_load_balance
$ ls /sys/kernel/debug/sched/domains/cpu*
/sys/kernel/debug/sched/domains/cpu0:

/sys/kernel/debug/sched/domains/cpu1:

/sys/kernel/debug/sched/domains/cpu2:

/sys/kernel/debug/sched/domains/cpu3:

/sys/kernel/debug/sched/domains/cpu4:

/sys/kernel/debug/sched/domains/cpu5:


I also checked that you can keep cpuset.sched_load_balance=0 at the root
and create exclusive child cpusets with different values of
sched_load_balance, giving you some CPUs attached to the NULL domain and
some others with a sched_domain hierarchy that stays within the cpuset span.

  reply	other threads:[~2021-07-14 23:44 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14 13:54 [RFC PATCH 0/6] cpuset: Allow to modify isolcpus through cpuset Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 1/6] pci: Decouple HK_FLAG_WQ and HK_FLAG_DOMAIN cpumask fetch Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 2/6] workqueue: " Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 3/6] net: " Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 4/6] sched/isolation: Split domain housekeeping mask from the rest Frederic Weisbecker
2021-07-14 13:54 ` [RFC PATCH 5/6] sched/isolation: Make HK_FLAG_DOMAIN mutable Frederic Weisbecker
2021-07-21 14:28   ` Vincent Donnefort
2021-07-14 13:54 ` [RFC PATCH 6/6] cpuset: Add cpuset.isolation_mask file Frederic Weisbecker
2021-07-14 16:31   ` Marcelo Tosatti
2021-07-19 13:26     ` Frederic Weisbecker
2021-07-19 15:41       ` Marcelo Tosatti
2021-07-14 16:52   ` Peter Zijlstra
2021-07-14 23:13     ` Frederic Weisbecker
2021-07-14 23:44       ` Valentin Schneider [this message]
2021-07-15  0:07         ` Frederic Weisbecker
2021-07-15  9:04       ` Peter Zijlstra
2021-07-19 13:17         ` Frederic Weisbecker
2021-07-16 18:02 ` [RFC PATCH 0/6] cpuset: Allow to modify isolcpus through cpuset Waiman Long
2021-07-19 13:57   ` Frederic Weisbecker

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=87o8b4mpfb.mognet@arm.com \
    --to=valentin.schneider@arm.com \
    --cc=abelits@marvell.com \
    --cc=cgroups@vger.kernel.org \
    --cc=cl@gentwo.de \
    --cc=frederic@kernel.org \
    --cc=juri.lelli@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=lizefan.x@bytedance.com \
    --cc=mtosatti@redhat.com \
    --cc=nilal@redhat.com \
    --cc=nsaenzju@redhat.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=tj@kernel.org \
    --subject='Re: [RFC PATCH 6/6] cpuset: Add cpuset.isolation_mask file' \
    /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

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).