From: Waiman Long <longman@redhat.com>
To: "Michal Koutný" <mkoutny@suse.com>, "Will Deacon" <will@kernel.org>
Cc: Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shuah Khan <shuah@kernel.org>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 3/5] cgroup/cpuset: Find another usable CPU if none found in current cpuset
Date: Sat, 25 Mar 2023 18:08:18 -0400 [thread overview]
Message-ID: <17e804ea-64b5-97e1-d5fa-571157e15746@redhat.com> (raw)
In-Reply-To: <20230324181936.5sf6xjc5a4vacuku@blackpad>
On 3/24/23 14:19, Michal Koutný wrote:
> On Fri, Mar 24, 2023 at 02:32:50PM +0000, Will Deacon <will@kernel.org> wrote:
>> So approaches such as killing tasks or rejecting system calls tend not
>> to work as well, since you inevitably get divergent behaviour leading
>> to functional breakage rather than e.g. performance anomalies.
> What about temporary performance drop from 100% to 0% aka freezing the
> tasks for the duration of the mismatching affinity config?
That can be a lot of extra work to freeze it. I will prefer something
simpler.
Without this patch, I believe it will lead to a cpumask of 0 which will
cause the scheduler to pick a fallback cpu. It looks like the fallback
code may be able to pick up the right cpu or it may panic the system
(less likely).
Cheers,
Longman
>
>
>> Having said that, the behaviour we currently have in mainline seems to
>> be alright, so please don't go out of your way to accomodate these SoCs.
> I see. (Just wondering what you think about the fourth option above.)
>
> Thanks,
> Michal
next prev parent reply other threads:[~2023-03-25 22:09 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 20:08 [PATCH 0/5] cgroup/cpuset: Miscellaneous updates Waiman Long
2023-03-06 20:08 ` [PATCH 1/5] cgroup/cpuset: Skip task update if hotplug doesn't affect current cpuset Waiman Long
2023-03-14 16:50 ` Michal Koutný
2023-03-14 18:20 ` Waiman Long
2023-03-06 20:08 ` [PATCH 2/5] cgroup/cpuset: Include offline CPUs when tasks' cpumasks in top_cpuset are updated Waiman Long
2023-03-14 17:34 ` Michal Koutný
2023-03-14 19:02 ` Waiman Long
2023-03-15 10:06 ` Michal Koutný
2023-03-15 14:39 ` Waiman Long
2023-03-06 20:08 ` [PATCH 3/5] cgroup/cpuset: Find another usable CPU if none found in current cpuset Waiman Long
2023-03-14 18:17 ` Michal Koutný
2023-03-14 20:22 ` Waiman Long
2023-03-17 12:27 ` Michal Koutný
2023-03-17 14:59 ` Waiman Long
2023-03-24 14:32 ` Will Deacon
2023-03-24 14:42 ` Waiman Long
2023-03-24 18:19 ` Michal Koutný
2023-03-25 22:08 ` Waiman Long [this message]
2023-03-06 20:08 ` [PATCH 4/5] cgroup/cpuset: Add CONFIG_DEBUG_CPUSETS config for cpuset testing Waiman Long
2023-03-06 20:08 ` [PATCH 5/5] cgroup/cpuset: Minor updates to test_cpuset_prs.sh Waiman Long
2023-03-07 16:16 ` Kamalesh Babulal
2023-03-15 16:24 ` [PATCH 0/5] cgroup/cpuset: Miscellaneous updates Will Deacon
2023-03-15 16:59 ` Waiman Long
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