linux-kernel - RE: [PATCH V3 0/6] event synthesization multithreading for perf record

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]

Message-ID: <37D7C6CF3E00A74B8858931C1DB2F077537D8E1C@SHSMSX103.ccr.corp.intel.com>
Date:   Tue, 24 Oct 2017 12:47:49 +0000
From:   "Liang, Kan" <kan.liang@...el.com>
To:     Jiri Olsa <jolsa@...hat.com>, Ingo Molnar <mingo@...nel.org>
CC:     "acme@...nel.org" <acme@...nel.org>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "jolsa@...nel.org" <jolsa@...nel.org>,
        "wangnan0@...wei.com" <wangnan0@...wei.com>,
        "hekuang@...wei.com" <hekuang@...wei.com>,
        "namhyung@...nel.org" <namhyung@...nel.org>,
        "alexander.shishkin@...ux.intel.com" 
        <alexander.shishkin@...ux.intel.com>,
        "Hunter, Adrian" <adrian.hunter@...el.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>
Subject: RE: [PATCH V3 0/6] event synthesization multithreading for perf
 record

> On Tue, Oct 24, 2017 at 11:22:00AM +0200, Ingo Molnar wrote:
> >
> > * Liang, Kan <kan.liang@...el.com> wrote:
> >
> > > For 'all', do you mean the whole process?
> >
> > Yeah.
> >
> > > I think that's the ultimate goal.  Eventually there will be per-CPU
> > > recording threads created at the beginning of perf record and go through
> the whole process.
> > > The plan is to do the multithreading step by step from the simplest case.
> > > Synthesizing stage is just a start.
> >
> > So, why not do it like the kernel did: add all the threads, create the
> > percpu files, and introduce a 'big perf lock' (big mutex) that is
> > taken for all the current non-threaded perf functionality. This should
> > be fairly straightforward to do and should be 'obviously correct'.
> >
> > _Then_ start doing the hard threading work on top of this, like
> > threading the synthesizing phase.
> >
> > Doing the whole per CPU thread setup/teardown for just the
> > synthesizing part of it looks like the wrong design.
> >
> > I.e. what I'm suggesting is no extra threading work, just organizing
> > it in a different fashion and increasing the life-time of the per CPU
> > threads from 'perf startup' to 'perf shutdown'.
> 
> I recently made some changes on threaded record, which are based on
> Namhyungs time* API, which is needed to read/sort the data afterwards
> 
> but I wasn't able to get any substantial and constant reduce of LOST events
> and then I got sidetracked and did not finish, but it's in here:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git perf/data
> 
> I'll try to rebase and send it out for comments
> 

I think I will wait for your patches, and rebase this series. :) 

Thanks,
Kan