From: Rahul Gopakumar <gopakumarr@vmware.com>
To: Valentin Schneider <valentin.schneider@arm.com>,
Abdul Anshad Azeez <aazees@vmware.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: "peterz@infradead.org" <peterz@infradead.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"juri.lelli@redhat.com" <juri.lelli@redhat.com>,
"vincent.guittot@linaro.org" <vincent.guittot@linaro.org>,
"rostedt@goodmis.org" <rostedt@goodmis.org>,
Rajender M <manir@vmware.com>
Subject: Re: [Linux Kernel 5.13 GA] ESXi Performance regression
Date: Thu, 5 Aug 2021 14:33:52 +0000 [thread overview]
Message-ID: <BYAPR05MB520669C6C1A8A522B1DE0EAAA4F29@BYAPR05MB5206.namprd05.prod.outlook.com> (raw)
In-Reply-To: <87a6m4kk4f.mognet@arm.com>
> sysctl_sched_wakeup_granularity's default value hasn't been touched since
> 2009:
>
> 172e082a9111 ("sched: Re-tune the scheduler latency defaults to decrease worst-case latencies")
>
> and the automagic scaling (see kernel/sched/fair.c::update_sysctl()) hasn't
> changed much either.
>
> What's likely to happen here is that you have a service in your distro (or
> somesuch) tweaking those values and since the incriminated commit moves
> those files to /sys/kernel/debug/sched/, said service doesn't do anything
> anymore.
Hi Valentin,
In our testing, we use RHEL 8.1 distro. It looks like tuned daemon updates
15ms (per tuned virtual-guest profile) in /proc/sys/kernel/sched_wakeup_granularity_ns
file during tuned's startup.
Now tuned daemon is not able to update the value as the commit moves those
files to debugs and thus sched_wakeup_granularity_ns file remains with the
default value.
Regards,
Rahul Gopakumar,
Performance Engineering,
VMware, Inc.
next prev parent reply other threads:[~2021-08-05 14:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 12:27 [Linux Kernel 5.13 GA] ESXi Performance regression Abdul Anshad Azeez
2021-07-30 13:26 ` Valentin Schneider
2021-08-05 14:33 ` Rahul Gopakumar [this message]
2021-08-05 14:58 ` Steven Rostedt
2021-08-05 15:05 ` Peter Zijlstra
2021-08-05 15:24 ` Steven Rostedt
2021-08-05 15:28 ` Peter Zijlstra
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