From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752026AbdJXLsA (ORCPT ); Tue, 24 Oct 2017 07:48:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48774 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751825AbdJXLr7 (ORCPT ); Tue, 24 Oct 2017 07:47:59 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 163667EBD3 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=jolsa@redhat.com Date: Tue, 24 Oct 2017 13:47:55 +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: <20171024114755.GA2716@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171024092200.wef6b66ecmhrvaja@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 [10.5.110.27]); Tue, 24 Oct 2017 11:47:59 +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 11:22:00AM +0200, Ingo Molnar wrote: > > * Liang, Kan wrote: > > > For 'all', do you mean the whole process? > > Yeah. > > > I think that's the ultimate goal. Eventually there will be per-CPU recording > > threads created at the beginning of perf record and go through the whole process. > > The plan is to do the multithreading step by step from the simplest case. > > Synthesizing stage is just a start. > > So, why not do it like the kernel did: add all the threads, create the percpu > files, and introduce a 'big perf lock' (big mutex) that is taken for all the > current non-threaded perf functionality. This should be fairly straightforward to > do and should be 'obviously correct'. > > _Then_ start doing the hard threading work on top of this, like threading the > synthesizing phase. > > Doing the whole per CPU thread setup/teardown for just the synthesizing part of it > looks like the wrong design. > > I.e. what I'm suggesting is no extra threading work, just organizing it in a > different fashion and increasing the life-time of the per CPU threads from 'perf > startup' to 'perf shutdown'. 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: git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git perf/data I'll try to rebase and send it out for comments jirka