From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932430AbdJYJAt (ORCPT ); Wed, 25 Oct 2017 05:00:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39840 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932217AbdJYJAq (ORCPT ); Wed, 25 Oct 2017 05:00:46 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 3D0A5C050049 Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=jolsa@redhat.com Date: Wed, 25 Oct 2017 11:00:34 +0200 From: Jiri Olsa To: Ingo Molnar Cc: "Liang, Kan" , "acme@kernel.org" , "mingo@redhat.com" , "linux-kernel@vger.kernel.org" , "peterz@infradead.org" , "jolsa@kernel.org" , "wangnan0@huawei.com" , "hekuang@huawei.com" , "namhyung@kernel.org" , "alexander.shishkin@linux.intel.com" , "Hunter, Adrian" , "ak@linux.intel.com" Subject: Re: [PATCH V3 0/6] event synthesization multithreading for perf record Message-ID: <20171025090034.GA27028@krava> References: <1508529934-369393-1-git-send-email-kan.liang@intel.com> <20171023114822.ijbixdkhysinlwqv@gmail.com> <37D7C6CF3E00A74B8858931C1DB2F077537D874E@SHSMSX103.ccr.corp.intel.com> <20171024092200.wef6b66ecmhrvaja@gmail.com> <20171024114755.GA2716@krava> <20171024125944.uswroptykcqrgjox@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171024125944.uswroptykcqrgjox@gmail.com> User-Agent: Mutt/1.9.1 (2017-09-22) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 25 Oct 2017 09:00:46 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 24, 2017 at 02:59:44PM +0200, Ingo Molnar wrote: > > * Jiri Olsa 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