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From: Peter Zijlstra <peterz@infradead.org>
To: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] psi: reduce calls to sched_clock() in psi
Date: Mon, 22 Mar 2021 08:45:12 +0100	[thread overview]
Message-ID: <YFhLCPzKlE2uk46k@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20210321205156.4186483-1-shakeelb@google.com>

On Sun, Mar 21, 2021 at 01:51:56PM -0700, Shakeel Butt wrote:
> We noticed that the cost of psi increases with the increase in the
> levels of the cgroups. Particularly the cost of cpu_clock() sticks out
> as the kernel calls it multiple times as it traverses up the cgroup
> tree. This patch reduces the calls to cpu_clock().
> 
> Performed perf bench on Intel Broadwell with 3 levels of cgroup.
> 
> Before the patch:
> 
> $ perf bench sched all
>  # Running sched/messaging benchmark...
>  # 20 sender and receiver processes per group
>  # 10 groups == 400 processes run
> 
>      Total time: 0.747 [sec]
> 
>  # Running sched/pipe benchmark...
>  # Executed 1000000 pipe operations between two processes
> 
>      Total time: 3.516 [sec]
> 
>        3.516689 usecs/op
>          284358 ops/sec
> 
> After the patch:
> 
> $ perf bench sched all
>  # Running sched/messaging benchmark...
>  # 20 sender and receiver processes per group
>  # 10 groups == 400 processes run
> 
>      Total time: 0.640 [sec]
> 
>  # Running sched/pipe benchmark...
>  # Executed 1000000 pipe operations between two processes
> 
>      Total time: 3.329 [sec]
> 
>        3.329820 usecs/op
>          300316 ops/sec
> 
> Signed-off-by: Shakeel Butt <shakeelb@google.com>

Thanks!

  reply	other threads:[~2021-03-22  7:46 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-21 20:51 [PATCH] psi: reduce calls to sched_clock() in psi Shakeel Butt
2021-03-22  7:45 ` Peter Zijlstra [this message]
2021-03-22 14:19 ` Johannes Weiner
2021-03-23 15:08 ` [tip: sched/core] psi: Reduce " tip-bot2 for Shakeel Butt

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