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

[Liang, Kan]

> On Tue, Oct 24, 2017 at 11:22:00AM +0200, Ingo Molnar wrote:
> >
> > * Liang, Kan <kan.liang@xxxxxxxxx> 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