From: Chengming Zhou <zhouchengming@bytedance.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: surenb@google.com, mingo@redhat.com, peterz@infradead.org,
tj@kernel.org, corbet@lwn.net, akpm@linux-foundation.org,
rdunlap@infradead.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, songmuchun@bytedance.com,
cgroups@vger.kernel.org
Subject: Re: [External] Re: [PATCH 8/9] sched/psi: add kernel cmdline parameter psi_inner_cgroup
Date: Tue, 26 Jul 2022 21:38:18 +0800 [thread overview]
Message-ID: <a2bd997b-fc81-ca1c-3d65-99fbd34cfba7@bytedance.com> (raw)
In-Reply-To: <Yt7KQc0nnOypB2b2@cmpxchg.org>
On 2022/7/26 00:52, Johannes Weiner wrote:
> On Thu, Jul 21, 2022 at 12:04:38PM +0800, Chengming Zhou wrote:
>> PSI accounts stalls for each cgroup separately and aggregates it
>> at each level of the hierarchy. This may case non-negligible overhead
>> for some workloads when under deep level of the hierarchy.
>>
>> commit 3958e2d0c34e ("cgroup: make per-cgroup pressure stall tracking configurable")
>> make PSI to skip per-cgroup stall accounting, only account system-wide
>> to avoid this each level overhead.
>>
>> For our use case, we also want leaf cgroup PSI accounted for userspace
>> adjustment on that cgroup, apart from only system-wide management.
>
> I hear the overhead argument. But skipping accounting in intermediate
> levels is a bit odd and unprecedented in the cgroup interface. Once we
> do this, it's conceivable people would like to do the same thing for
> other stats and accounting, like for instance memory.stat.
Right, it's a bit odd... We don't use PSI stats in intermediate levels
in our use case, but don't know what other use scenarios are. If they are
useful for other people, this patch can be dropped.
Thanks.
>
> Tejun, what are your thoughts on this?
next prev parent reply other threads:[~2022-07-26 13:38 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-21 4:04 [PATCH 0/9] sched/psi: some optimization and extension Chengming Zhou
2022-07-21 4:04 ` [PATCH 1/9] sched/psi: fix periodic aggregation shut off Chengming Zhou
2022-07-25 15:34 ` Johannes Weiner
2022-07-25 15:39 ` Johannes Weiner
2022-07-26 13:28 ` Chengming Zhou
2022-07-21 4:04 ` [PATCH 2/9] sched/psi: optimize task switch inside shared cgroups again Chengming Zhou
2022-07-21 4:04 ` [PATCH 3/9] sched/psi: move private helpers to sched/stats.h Chengming Zhou
2022-07-25 16:39 ` Johannes Weiner
2022-07-21 4:04 ` [PATCH 4/9] sched/psi: don't change task psi_flags when migrate CPU/group Chengming Zhou
2022-07-21 4:04 ` [PATCH 5/9] sched/psi: don't create cgroup PSI files when psi_disabled Chengming Zhou
2022-07-25 16:41 ` Johannes Weiner
2022-07-21 4:04 ` [PATCH 6/9] sched/psi: save percpu memory when !psi_cgroups_enabled Chengming Zhou
2022-07-25 16:47 ` Johannes Weiner
2022-07-21 4:04 ` [PATCH 7/9] sched/psi: cache parent psi_group to speed up groups iterate Chengming Zhou
2022-07-21 4:04 ` [PATCH 8/9] sched/psi: add kernel cmdline parameter psi_inner_cgroup Chengming Zhou
2022-07-25 16:52 ` Johannes Weiner
2022-07-26 13:38 ` Chengming Zhou [this message]
2022-07-26 17:54 ` Tejun Heo
2022-08-03 12:17 ` Chengming Zhou
2022-08-03 17:58 ` Tejun Heo
2022-08-03 19:22 ` Johannes Weiner
2022-08-03 19:48 ` Tejun Heo
2022-08-04 13:51 ` Chengming Zhou
2022-08-04 16:56 ` Johannes Weiner
2022-08-04 2:02 ` Chengming Zhou
2022-07-21 4:04 ` [PATCH 9/9] sched/psi: add PSI_IRQ to track IRQ/SOFTIRQ pressure Chengming Zhou
2022-07-21 10:00 ` kernel test robot
2022-07-21 22:10 ` kernel test robot
2022-07-22 3:30 ` Abel Wu
2022-07-22 6:13 ` Chengming Zhou
2022-07-22 7:14 ` Abel Wu
2022-07-22 7:33 ` Chengming Zhou
2022-07-25 18:26 ` Johannes Weiner
2022-07-26 13:55 ` [External] " Chengming Zhou
2022-07-27 11:28 ` Chengming Zhou
2022-07-27 13:00 ` Johannes Weiner
2022-07-27 15:09 ` Chengming Zhou
2022-07-27 16:07 ` 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=a2bd997b-fc81-ca1c-3d65-99fbd34cfba7@bytedance.com \
--to=zhouchengming@bytedance.com \
--cc=akpm@linux-foundation.org \
--cc=cgroups@vger.kernel.org \
--cc=corbet@lwn.net \
--cc=hannes@cmpxchg.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=rdunlap@infradead.org \
--cc=songmuchun@bytedance.com \
--cc=surenb@google.com \
--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;
as well as URLs for NNTP newsgroup(s).