linux-kernel - Re: [Linux Kernel 5.13 GA] ESXi Performance regression

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Message-ID: <YQv+HHwrMmiUYZ4+@hirez.programming.kicks-ass.net>
Date:   Thu, 5 Aug 2021 17:05:00 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Rahul Gopakumar <gopakumarr@...are.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Abdul Anshad Azeez <aazees@...are.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "juri.lelli@...hat.com" <juri.lelli@...hat.com>,
        "vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
        Rajender M <manir@...are.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [Linux Kernel 5.13 GA] ESXi Performance regression

On Thu, Aug 05, 2021 at 10:58:53AM -0400, Steven Rostedt wrote:
> On Thu, 5 Aug 2021 14:33:52 +0000
> Rahul Gopakumar <gopakumarr@...are.com> wrote:
> 
> > 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.
> 
> Hmm, is this a user space breakage?

All those files were under CONFIG_SCHED_DEBUG and a !DEBUG build would
not have them to begin with.