From: Daniel Bristot de Oliveira <bristot@redhat.com>
To: Juri Lelli <juri.lelli@redhat.com>, Waiman Long <longman@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>, Qais Yousef <qyousef@layalina.io>,
Tejun Heo <tj@kernel.org>, Zefan Li <lizefan.x@bytedance.com>,
Johannes Weiner <hannes@cmpxchg.org>, Hao Luo <haoluo@google.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org, luca.abeni@santannapisa.it,
claudio@evidence.eu.com, tommaso.cucinotta@santannapisa.it,
mathieu.poirier@linaro.org, cgroups@vger.kernel.org,
Vincent Guittot <vincent.guittot@linaro.org>,
Wei Wang <wvw@google.com>, Rick Yiu <rickyiu@google.com>,
Quentin Perret <qperret@google.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Sudeep Holla <sudeep.holla@arm.com>
Subject: Re: [PATCH 2/6] sched/cpuset: Bring back cpuset_mutex
Date: Wed, 26 Apr 2023 16:31:09 +0200 [thread overview]
Message-ID: <10fdfdd8-06bc-0f35-0fea-e604aa5c103a@redhat.com> (raw)
In-Reply-To: <ZEkRq9iGkYP/8T5w@localhost.localdomain>
On 4/26/23 13:57, Juri Lelli wrote:
> On 04/04/23 13:31, Waiman Long wrote:
>> On 3/29/23 08:55, Juri Lelli wrote:
>>> Turns out percpu_cpuset_rwsem - commit 1243dc518c9d ("cgroup/cpuset:
>>> Convert cpuset_mutex to percpu_rwsem") - wasn't such a brilliant idea,
>>> as it has been reported to cause slowdowns in workloads that need to
>>> change cpuset configuration frequently and it is also not implementing
>>> priority inheritance (which causes troubles with realtime workloads).
>>>
>>> Convert percpu_cpuset_rwsem back to regular cpuset_mutex. Also grab it
>>> only for SCHED_DEADLINE tasks (other policies don't care about stable
>>> cpusets anyway).
>>>
>>> Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
>> I am thinking that maybe we should switch the percpu rwsem to a regular
>> rwsem as there are cases where a read lock is sufficient. This will also
>> avoid the potential PREEMPT_RT problem with PI and reduce the time it needs
>> to take a write lock.
> I'm not a big fan of rwsems for reasons like
> https://lore.kernel.org/lkml/20230321161140.HMcQEhHb@linutronix.de/, so
> I'd vote for a standard mutex unless we have a strong argument and/or
> numbers.
+1
-- Daniel
next prev parent reply other threads:[~2023-04-26 14:32 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-29 12:55 [PATCH 0/6] sched/deadline: cpuset: Rework DEADLINE bandwidth restoration Juri Lelli
2023-03-29 12:55 ` [PATCH 1/6] cgroup/cpuset: Rename functions dealing with DEADLINE accounting Juri Lelli
2023-04-04 20:05 ` Qais Yousef
2023-03-29 12:55 ` [PATCH 2/6] sched/cpuset: Bring back cpuset_mutex Juri Lelli
2023-04-04 17:31 ` Waiman Long
2023-04-26 11:57 ` Juri Lelli
2023-04-26 14:05 ` Waiman Long
2023-04-27 2:58 ` Xuewen Yan
2023-04-27 5:53 ` Juri Lelli
2023-04-27 11:50 ` Xuewen Yan
2023-04-28 11:22 ` Qais Yousef
2023-04-26 14:31 ` Daniel Bristot de Oliveira [this message]
2023-04-04 20:05 ` Qais Yousef
2023-03-29 12:55 ` [PATCH 3/6] sched/cpuset: Keep track of SCHED_DEADLINE task in cpusets Juri Lelli
2023-04-04 20:06 ` Qais Yousef
2023-10-09 11:43 ` Xia Fukun
2023-10-09 15:26 ` Waiman Long
2023-03-29 12:55 ` [PATCH 4/6] sched/deadline: Create DL BW alloc, free & check overflow interface Juri Lelli
2023-03-29 14:24 ` Waiman Long
2023-03-29 12:55 ` [PATCH 5/6] cgroup/cpuset: Free DL BW in case can_attach() fails Juri Lelli
2023-03-29 14:25 ` Waiman Long
2023-03-29 14:31 ` Waiman Long
2023-03-29 16:39 ` Dietmar Eggemann
2023-03-29 18:09 ` Waiman Long
2023-03-30 15:14 ` Dietmar Eggemann
2023-03-30 16:13 ` Waiman Long
2023-03-29 12:55 ` [PATCH 6/6] cgroup/cpuset: Iterate only if DEADLINE tasks are present Juri Lelli
2023-04-04 20:06 ` Qais Yousef
2023-04-26 11:58 ` Juri Lelli
2023-03-29 14:34 ` [PATCH 0/6] sched/deadline: cpuset: Rework DEADLINE bandwidth restoration Waiman Long
2023-03-29 16:02 ` [PATCH 6/7] cgroup/cpuset: Protect DL BW data against parallel cpuset_attach() Waiman Long
2023-03-29 16:05 ` Waiman Long
2023-03-30 13:34 ` Dietmar Eggemann
2023-04-04 20:09 ` [PATCH 0/6] sched/deadline: cpuset: Rework DEADLINE bandwidth restoration Qais Yousef
2023-04-18 14:11 ` Qais Yousef
2023-04-18 14:31 ` Waiman Long
2023-04-20 14:15 ` Juri Lelli
2023-08-20 15:21 [PATCH 0/6] Backport rework of deadline bandwidth restoration for 5.10.y Qais Yousef
2023-08-20 15:21 ` [PATCH 2/6] sched/cpuset: Bring back cpuset_mutex Qais Yousef
2023-08-20 15:22 [PATCH 0/6] Backport rework of deadline bandwidth restoration for 5.15.y Qais Yousef
2023-08-20 15:22 ` [PATCH 2/6] sched/cpuset: Bring back cpuset_mutex Qais Yousef
2023-08-20 15:24 [PATCH 0/6] Backport rework of deadline bandwidth restoration for 6.1.y Qais Yousef
2023-08-20 15:24 ` [PATCH 2/6] sched/cpuset: Bring back cpuset_mutex Qais Yousef
2023-08-21 22:19 [PATCH 0/6] Backport rework of deadline bandwidth restoration for 6.4.y Qais Yousef
2023-08-21 22:19 ` [PATCH 2/6] sched/cpuset: Bring back cpuset_mutex Qais Yousef
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