From: Qais Yousef <qyousef@layalina.io>
To: Waiman Long <longman@redhat.com>
Cc: stable@vger.kernel.org, Juri Lelli <juri.lelli@redhat.com>,
Tejun Heo <tj@kernel.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Ingo Molnar <mingo@kernel.org>, Hao Luo <haoluo@google.com>,
John Stultz <jstultz@google.com>,
cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/6] Backport rework of deadline bandwidth restoration for 5.10.y
Date: Mon, 21 Aug 2023 00:02:57 +0100 [thread overview]
Message-ID: <20230820230257.gmcmjuuirzq6xs52@airbuntu> (raw)
In-Reply-To: <883a5a4f-b34e-689c-2fbd-7bf03db532eb@redhat.com>
On 08/20/23 12:24, Waiman Long wrote:
>
> On 8/20/23 11:21, Qais Yousef wrote:
> > This is a backport of the series that fixes the way deadline bandwidth
> > restoration is done which is causing noticeable delay on resume path. It also
> > converts the cpuset lock back into a mutex which some users on Android too.
> > I lack the details but AFAIU the read/write semaphore was slower on high
> > contention.
>
> Note that it was a percpu rwsem before this patch series. It was not a
> regular rwsem. Percpu rwsem isn't designed to handle high write lock
> contention. A regular rwsem should be similar to mutex in performance when
> handling high write lock contention.
Thanks a lot for the clarification Waiman! Much appreciated.
Cheers
--
Qais Yousef
prev parent reply other threads:[~2023-08-20 23:02 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-20 15:21 [PATCH 0/6] Backport rework of deadline bandwidth restoration for 5.10.y Qais Yousef
[not found] ` <20230820152144.517461-1-qyousef-wp2msK0BRk8tq7phqP6ubQ@public.gmane.org>
2023-08-20 15:21 ` [PATCH 1/6] cgroup/cpuset: Rename functions dealing with DEADLINE accounting Qais Yousef
2023-08-20 15:21 ` [PATCH 2/6] sched/cpuset: Bring back cpuset_mutex Qais Yousef
2023-08-20 15:21 ` [PATCH 6/6] cgroup/cpuset: Free DL BW in case can_attach() fails Qais Yousef
2023-08-20 15:21 ` [PATCH 3/6] sched/cpuset: Keep track of SCHED_DEADLINE task in cpusets Qais Yousef
2023-08-20 15:21 ` [PATCH 4/6] cgroup/cpuset: Iterate only if DEADLINE tasks are present Qais Yousef
2023-08-20 15:21 ` [PATCH 5/6] sched/deadline: Create DL BW alloc, free & check overflow interface Qais Yousef
2023-08-20 16:24 ` [PATCH 0/6] Backport rework of deadline bandwidth restoration for 5.10.y Waiman Long
2023-08-20 23:02 ` Qais Yousef [this message]
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