From: Jiri Olsa <jolsa@redhat.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: "Liang, Kan" <kan.liang@intel.com>,
"acme@kernel.org" <acme@kernel.org>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"peterz@infradead.org" <peterz@infradead.org>,
"jolsa@kernel.org" <jolsa@kernel.org>,
"wangnan0@huawei.com" <wangnan0@huawei.com>,
"hekuang@huawei.com" <hekuang@huawei.com>,
"namhyung@kernel.org" <namhyung@kernel.org>,
"alexander.shishkin@linux.intel.com"
<alexander.shishkin@linux.intel.com>,
"Hunter, Adrian" <adrian.hunter@intel.com>,
"ak@linux.intel.com" <ak@linux.intel.com>
Subject: Re: [PATCH V3 0/6] event synthesization multithreading for perf record
Date: Wed, 25 Oct 2017 11:00:34 +0200 [thread overview]
Message-ID: <20171025090034.GA27028@krava> (raw)
In-Reply-To: <20171024125944.uswroptykcqrgjox@gmail.com>
On Tue, Oct 24, 2017 at 02:59:44PM +0200, Ingo Molnar wrote:
>
> * 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?
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
jirka
next prev parent reply other threads:[~2017-10-25 9:00 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-20 20:05 [PATCH V3 0/6] event synthesization multithreading for perf record kan.liang
2017-10-20 20:05 ` [PATCH V3 1/6] perf tools: pass thread info to process function kan.liang
2017-10-20 20:05 ` [PATCH V3 2/6] perf tools: pass thread info in event synthesization kan.liang
2017-10-20 20:05 ` [PATCH V3 3/6] perf tools: expose copyfile_offset() kan.liang
2017-10-20 20:05 ` [PATCH V3 4/6] perf tools: add perf_data_file__open_tmp kan.liang
2017-10-23 16:13 ` Jiri Olsa
2017-10-23 16:19 ` Liang, Kan
2017-10-23 16:26 ` Jiri Olsa
2017-10-23 18:05 ` Liang, Kan
2017-10-24 7:26 ` Jiri Olsa
2017-10-24 7:26 ` Jiri Olsa
2017-10-20 20:05 ` [PATCH V3 5/6] perf record: synthesize event multithreading support kan.liang
2017-10-20 20:05 ` [PATCH V3 6/6] perf record: add option to set the number of thread for event synthesize kan.liang
2017-10-23 11:48 ` [PATCH V3 0/6] event synthesization multithreading for perf record Ingo Molnar
2017-10-23 13:43 ` Liang, Kan
2017-10-23 14:25 ` acme
2017-10-23 18:45 ` Liang, Kan
2017-10-24 9:22 ` Ingo Molnar
2017-10-24 11:47 ` Jiri Olsa
2017-10-24 12:47 ` Liang, Kan
2017-10-24 12:59 ` Ingo Molnar
2017-10-24 13:08 ` Arnaldo Carvalho de Melo
2017-10-24 13:25 ` Ingo Molnar
2017-10-25 2:35 ` Namhyung Kim
2017-10-25 9:02 ` Jiri Olsa
2017-10-25 9:00 ` Jiri Olsa [this message]
2017-10-25 9:07 ` Ingo Molnar
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