* Jiri Olsa <jo...@redhat.com> wrote: > On Tue, Oct 24, 2017 at 02:59:44PM +0200, Ingo Molnar wrote: > > > > * Jiri Olsa <jo...@redhat.com> 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 > > > > etc. > > > > Is this how you implemented it? > > in a way ;-) but I made it more generic and let record create just > few threads and let them share cpu subset.. and so there was no binding > > > > > If the threads in the thread pool are just free-running then the scheduler > > might > > not migrate it to the 'right' CPU that is streaming the perf events and > > there will > > be a lot of cross-talking between CPUs. > > ok it's easy to add binding now and 1:1 thread:cpu mapping.. I'll retry
Please Cc: me - this is a really interesting aspect of perf scalability! Thanks, Ingo