linux-kernel - Re: [PATCH 1/2] sched/uclamp: Add a new sysctl to control RT default boost value

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Date:   Fri, 29 May 2020 17:57:39 +0100
From:   Mel Gorman <mgorman@...e.de>
To:     Qais Yousef <qais.yousef@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Jonathan Corbet <corbet@....net>,
        Juri Lelli <juri.lelli@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ben Segall <bsegall@...gle.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>,
        Quentin Perret <qperret@...gle.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Patrick Bellasi <patrick.bellasi@...bug.net>,
        Pavan Kondeti <pkondeti@...eaurora.org>,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/2] sched/uclamp: Add a new sysctl to control RT default
 boost value

> > A lot of the uclamp functions appear to be inlined so it is not be
> > particularly obvious from a raw profile but it shows up in the annotated
> > profile in activate_task and dequeue_task for example. In the case of
> > dequeue_task, uclamp_rq_dec_id() is extremely expensive according to the
> > annotated profile.
> > 
> > I'm afraid I did not dig into this deeply once I knew I could just disable
> > it even within the distribution.
> 
> Could by any chance the vmlinux (with debug symbols hopefully) and perf.dat are
> still lying around to share?
> 

I didn't preserve the vmlinux files. I can recreate them if you have
problems reproducing this locally. The "perf archive" files and profile
data can be downloaded at
http://www.skynet.ie/~mel/postings/netperf-20200529/profile.tar.gz which
should be enough for an annotated profile to compare with a local run.

-- 
Mel Gorman
SUSE Labs