linux-kernel - Re: [RFC 00/10] perf: Add cputime events/metrics

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 6 Jun 2018 16:10:18 -0700
From:   Andi Kleen <andi@...stfloor.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Stephane Eranian <eranian@...gle.com>,
        Milian Wolff <milian.wolff@...b.com>,
        Andi Kleen <andi@...stfloor.org>,
        Frederic Weisbecker <frederic@...nel.org>
Subject: Re: [RFC 00/10] perf: Add cputime events/metrics

> I had some issues with IDLE counter being miscounted due to stopping
> of the idle tick. I tried to solve it in this patch (it's part of the
> patchset):
>   perf/cputime: Don't stop idle tick if there's live cputime event
> 
> but I'm pretty sure it's wrong and there's better solution.

At least on intel we already have hardware counters for different idle
states. You just would need to add them and convert to the same
unit.

But of course it's still useful when this is not available.

> My current plan is now to read those counters in perf top/record/report
> to show (at least) the idle percentage for the current profile.

It's useful. Thanks for working on it. I was thinking about doing
something similar for some time.

-Andi