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

[Jiri Olsa]

On Wed, Oct 25, 2017 at 11:35:39AM +0900, Namhyung Kim wrote:
> Hi Ingo,
> 
> On Tue, Oct 24, 2017 at 03:25:23PM +0200, Ingo Molnar wrote:
> > 
> > * Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
> > 
> > > Em Tue, Oct 24, 2017 at 02:59:44PM +0200, Ingo Molnar escreveu:
> > > > 
> > > > * Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> > > > 
> > > > > 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:
> > > > 
> > > > So, in the context of system-wide profiling, the way that would work best I think 
> > > > is the following:
> > > > 
> > > >   thread #0 binds itself to CPU#0 (via sched_setaffinity) and creates a per-CPU event on CPU#0
> > > >   thread #1 binds itself to CPU#1 (via sched_setaffinity) and creates a per-CPU event on CPU#1
> > > >   thread #2 binds itself to CPU#2 (via sched_setaffinity) and creates a per-CPU event on CPU#2
> > > 
> > > Right, that is how I think it should be done as well, and those will
> > > just dump on separate files, in a per session directory, with an extra
> > > file for the session details, in what is now the header.
> > 
> > Yes. Also note how easy to examine such a directory structure is - I'd suggest 
> > making all the session details textual eventually. I.e. only the ring-buffers 
> > should be binary, the rest should be arch-independent text encoding.
> > 
> > It's also very extensible.
> 
> Agreed.
> 
> Also for multithread work, conversion to directory should be the first
> step IMHO.

yes, but thats what we already have with yours (Namhyung's) HEADER_DATA_INDEX

jirka