Messages in this thread | | | Date | Tue, 24 Oct 2017 14:59:44 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH V3 0/6] event synthesization multithreading for perf record |
| |
* Jiri Olsa <jolsa@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?
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.
Inherited events (default 'perf record') is tougher.
Thanks,
Ingo
| |