From: "Michal Koutný" <mkoutny@suse.com>
To: "Moessbauer, Felix" <felix.moessbauer@siemens.com>
Cc: "longman@redhat.com" <longman@redhat.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
"corbet@lwn.net" <corbet@lwn.net>,
"frederic@kernel.org" <frederic@kernel.org>,
"guro@fb.com" <guro@fb.com>,
"hannes@cmpxchg.org" <hannes@cmpxchg.org>,
"juri.lelli@redhat.com" <juri.lelli@redhat.com>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-kselftest@vger.kernel.org"
<linux-kselftest@vger.kernel.org>,
"lizefan.x@bytedance.com" <lizefan.x@bytedance.com>,
"mtosatti@redhat.com" <mtosatti@redhat.com>,
"pauld@redhat.com" <pauld@redhat.com>,
"peterz@infradead.org" <peterz@infradead.org>,
"shuah@kernel.org" <shuah@kernel.org>,
"tj@kernel.org" <tj@kernel.org>,
"jan.kiszka@siemens.com" <jan.kiszka@siemens.com>,
"henning.schild@siemens.com" <henning.schild@siemens.com>
Subject: Re: [PATCH v8 0/6] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus
Date: Wed, 10 Nov 2021 19:15:58 +0100 [thread overview]
Message-ID: <20211110181558.GB51149@blackbody.suse.cz> (raw)
In-Reply-To: <AM9PR10MB4869C14EAE01B87C0037BF6A89939@AM9PR10MB4869.EURPRD10.PROD.OUTLOOK.COM>
On Wed, Nov 10, 2021 at 03:21:54PM +0000, "Moessbauer, Felix" <felix.moessbauer@siemens.com> wrote:
> 2. Threads can be started on non-rt CPUs and then bound to a specific rt CPU.
> This binding can be specified before thread creation via pthread_create.
> By that, you can make sure that at no point in time a thread has a
> "forbidden" CPU in its affinities.
It should boil down to some clone$version(2) and sched_setaffinity(2)
calls, so strictly speaking even with pthread_create(3) the thread is
shortly running with the parent's affinity.
> With cgroup2, you cannot guarantee the second aspect, as thread
> creation and moving to a cgroup is not an atomic operation.
As suggested by others, CLONE_INTO_CGROUP (into cpuset cgroup) can
actually "hide" the migration into the clone3() call.
> At creation time, you cannot set the final affinity mask (as you
> create it in the non-rt group and there the CPU is not in the
> cpuset.cpus).
> Once you move the thread to the rt cgroup, it has a default mask and
> by that can be executed on other rt cores.
Good point. Perhaps you could work this around by having another level
of (non-root partition) cpuset cgroups for individual CPUs? (Maybe
there's more clever approach, this is just first to come into my mind.)
Michal
WARNING: multiple messages have this Message-ID (diff)
From: "Michal Koutný" <mkoutny-IBi9RG/b67k@public.gmane.org>
To: "Moessbauer,
Felix" <felix.moessbauer-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>
Cc: "longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
<longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org"
<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
"cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"corbet-T1hC0tSOHrs@public.gmane.org"
<corbet-T1hC0tSOHrs@public.gmane.org>,
"frederic-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org"
<frederic-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
"guro-b10kYP2dOMg@public.gmane.org"
<guro-b10kYP2dOMg@public.gmane.org>,
"hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org"
<hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>,
"juri.lelli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
<juri.lelli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"linux-kselftest-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kselftest-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
"lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org"
<lizefan.x-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>,
"mtosatti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
<mtosatti-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"pauld-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
<pauld-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org"
<peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
"shuah-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org"
<shuah-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
t
Subject: Re: [PATCH v8 0/6] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus
Date: Wed, 10 Nov 2021 19:15:58 +0100 [thread overview]
Message-ID: <20211110181558.GB51149@blackbody.suse.cz> (raw)
In-Reply-To: <AM9PR10MB4869C14EAE01B87C0037BF6A89939-M49tMopaQCDO+/9PLUklKbUAtUbAAahqZmpNikb/MY7jO8Y7rvWZVA@public.gmane.org>
On Wed, Nov 10, 2021 at 03:21:54PM +0000, "Moessbauer, Felix" <felix.moessbauer-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org> wrote:
> 2. Threads can be started on non-rt CPUs and then bound to a specific rt CPU.
> This binding can be specified before thread creation via pthread_create.
> By that, you can make sure that at no point in time a thread has a
> "forbidden" CPU in its affinities.
It should boil down to some clone$version(2) and sched_setaffinity(2)
calls, so strictly speaking even with pthread_create(3) the thread is
shortly running with the parent's affinity.
> With cgroup2, you cannot guarantee the second aspect, as thread
> creation and moving to a cgroup is not an atomic operation.
As suggested by others, CLONE_INTO_CGROUP (into cpuset cgroup) can
actually "hide" the migration into the clone3() call.
> At creation time, you cannot set the final affinity mask (as you
> create it in the non-rt group and there the CPU is not in the
> cpuset.cpus).
> Once you move the thread to the rt cgroup, it has a default mask and
> by that can be executed on other rt cores.
Good point. Perhaps you could work this around by having another level
of (non-root partition) cpuset cgroups for individual CPUs? (Maybe
there's more clever approach, this is just first to come into my mind.)
Michal
next prev parent reply other threads:[~2021-11-10 18:16 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-18 14:36 [PATCH v8 0/6] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Waiman Long
2021-10-18 14:36 ` Waiman Long
2021-10-18 14:36 ` [PATCH v8 1/6] cgroup/cpuset: Allow no-task partition to have empty cpuset.cpus.effective Waiman Long
2021-10-18 14:36 ` Waiman Long
2021-10-18 14:36 ` [PATCH v8 2/6] cgroup/cpuset: Refining features and constraints of a partition Waiman Long
2021-10-18 14:36 ` Waiman Long
2021-10-18 14:36 ` [PATCH v8 3/6] cgroup/cpuset: Add a new isolated cpus.partition type Waiman Long
2021-10-18 14:36 ` [PATCH v8 4/6] cgroup/cpuset: Show invalid partition reason string Waiman Long
2021-10-18 14:36 ` [PATCH v8 5/6] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst Waiman Long
2021-11-15 19:31 ` Michal Koutný
2021-11-15 19:31 ` Michal Koutný
2021-11-15 20:11 ` Tejun Heo
2021-11-15 20:11 ` Tejun Heo
2021-11-15 21:27 ` Waiman Long
2021-11-15 21:27 ` Waiman Long
2021-11-15 21:10 ` Waiman Long
2021-11-16 17:54 ` Michal Koutný
2021-11-30 15:35 ` Waiman Long
2021-11-30 17:11 ` Tejun Heo
2021-11-30 17:11 ` Tejun Heo
2021-12-01 3:56 ` Waiman Long
2021-12-01 14:13 ` Michal Koutný
2021-12-01 14:13 ` Michal Koutný
2021-12-01 14:56 ` Waiman Long
2021-12-01 14:56 ` Waiman Long
2021-12-01 16:39 ` Tejun Heo
2021-12-01 17:49 ` Waiman Long
2021-12-01 17:49 ` Waiman Long
2021-12-01 14:26 ` Waiman Long
2021-12-01 14:26 ` Waiman Long
2021-12-01 16:46 ` Tejun Heo
2021-12-01 16:46 ` Tejun Heo
2021-12-01 18:05 ` Waiman Long
2021-12-02 1:28 ` Waiman Long
2021-12-03 18:25 ` Michal Koutný
2021-12-03 18:25 ` Michal Koutný
2021-12-03 19:27 ` Waiman Long
2021-10-18 14:36 ` [PATCH v8 6/6] kselftest/cgroup: Add cpuset v2 partition root state test Waiman Long
2021-10-18 14:36 ` Waiman Long
2021-10-27 23:05 ` [PATCH v8 0/6] cgroup/cpuset: Add new cpuset partition type & empty effecitve cpus Waiman Long
2021-11-10 11:13 ` Felix Moessbauer
2021-11-10 13:21 ` Marcelo Tosatti
2021-11-10 13:56 ` Michal Koutný
2021-11-10 15:21 ` Moessbauer, Felix
2021-11-10 15:21 ` Moessbauer, Felix
2021-11-10 16:10 ` Marcelo Tosatti
2021-11-10 16:10 ` Marcelo Tosatti
2021-11-10 16:14 ` Marcelo Tosatti
2021-11-10 16:14 ` Marcelo Tosatti
2021-11-10 16:15 ` Jan Kiszka
2021-11-10 16:15 ` Jan Kiszka
2021-11-10 17:29 ` Marcelo Tosatti
2021-11-10 17:29 ` Marcelo Tosatti
2021-11-10 18:30 ` Waiman Long
2021-11-10 18:30 ` Waiman Long
2021-11-10 17:52 ` Michal Koutný
2021-11-10 17:52 ` Michal Koutný
2021-11-10 18:04 ` Jan Kiszka
2021-11-10 18:04 ` Jan Kiszka
2021-11-10 18:15 ` Michal Koutný [this message]
2021-11-10 18:15 ` Michal Koutný
2021-11-10 15:20 ` Waiman Long
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=20211110181558.GB51149@blackbody.suse.cz \
--to=mkoutny@suse.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=corbet@lwn.net \
--cc=felix.moessbauer@siemens.com \
--cc=frederic@kernel.org \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--cc=henning.schild@siemens.com \
--cc=jan.kiszka@siemens.com \
--cc=juri.lelli@redhat.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=lizefan.x@bytedance.com \
--cc=longman@redhat.com \
--cc=mtosatti@redhat.com \
--cc=pauld@redhat.com \
--cc=peterz@infradead.org \
--cc=shuah@kernel.org \
--cc=tj@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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.