From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Jonathan Corbet <corbet@lwn.net>, Shuah Khan <shuah@kernel.org>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Roman Gushchin <guro@fb.com>, Phil Auld <pauld@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>
Subject: Re: [PATCH 2/5] cgroup/cpuset: Add new cpus.partition type with no load balancing
Date: Thu, 10 Jun 2021 21:00:09 +0200 [thread overview]
Message-ID: <YMJhObisfWJ1PzgR@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210603212416.25934-3-longman@redhat.com>
On Thu, Jun 03, 2021 at 05:24:13PM -0400, Waiman Long wrote:
> Cpuset v1 uses the sched_load_balance control file to determine if load
> balancing should be enabled. Cpuset v2 gets rid of sched_load_balance
> as its use may require disabling load balancing at cgroup root.
>
> For workloads that require very low latency like DPDK, the latency
> jitters caused by periodic load balancing may exceed the desired
> latency limit.
>
> When cpuset v2 is in use, the only way to avoid this latency cost is to
> use the "isolcpus=" kernel boot option to isolate a set of CPUs. After
> the kernel boot, however, there is no way to add or remove CPUs from
> this isolated set. For workloads that are more dynamic in nature, that
> means users have to provision enough CPUs for the worst case situation
> resulting in excess idle CPUs.
Also, can we change isolcpus to create a default cgroup hierarchy
instead of being the fugly hack that it is? I really hate isolcpus with
a passion, it needs to die.
next prev parent reply other threads:[~2021-06-10 19:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-03 21:24 [PATCH 0/5] cgroup/cpuset: Enable cpuset partition with no load balancing Waiman Long
2021-06-03 21:24 ` [PATCH 1/5] cgroup/cpuset: Don't call validate_change() for some flag changes Waiman Long
2021-06-16 20:39 ` Tejun Heo
2021-06-17 2:53 ` Waiman Long
2021-06-03 21:24 ` [PATCH 2/5] cgroup/cpuset: Add new cpus.partition type with no load balancing Waiman Long
2021-06-10 18:50 ` Peter Zijlstra
2021-06-10 19:16 ` Waiman Long
2021-06-10 19:39 ` Peter Zijlstra
2021-06-10 19:00 ` Peter Zijlstra [this message]
2021-06-10 19:21 ` Waiman Long
2021-06-16 20:47 ` Tejun Heo
2021-06-17 2:57 ` Waiman Long
2021-06-03 21:24 ` [PATCH 3/5] cgroup/cpuset: Allow non-top parent partition root to distribute out all CPUs Waiman Long
2021-06-16 20:57 ` Tejun Heo
2021-06-17 20:45 ` Waiman Long
2021-06-03 21:24 ` [PATCH 4/5] cgroup/cpuset: Update description of cpuset.cpus.partition in cgroup-v2.rst Waiman Long
2021-06-03 21:24 ` [PATCH 5/5] kselftest/cgroup: Add cpuset v2 partition root state test Waiman Long
2021-06-10 14:19 ` [PATCH 0/5] cgroup/cpuset: Enable cpuset partition with no load balancing Phil Auld
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=YMJhObisfWJ1PzgR@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=corbet@lwn.net \
--cc=guro@fb.com \
--cc=hannes@cmpxchg.org \
--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=pauld@redhat.com \
--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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox