Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751372AbdISITF (ORCPT ); Tue, 19 Sep 2017 04:19:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37792 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750884AbdISITE (ORCPT ); Tue, 19 Sep 2017 04:19:04 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 509397E423 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, 19 Sep 2017 10:19:01 +0200 From: Jiri Olsa To: Arnaldo Carvalho de Melo Cc: kan.liang@intel.com, peterz@infradead.org, mingo@redhat.com, linux-kernel@vger.kernel.org, jolsa@kernel.org, namhyung@kernel.org, adrian.hunter@intel.com, lukasz.odzioba@intel.com, ak@linux.intel.com Subject: Re: [PATCH RFC V2 00/10] perf top optimization Message-ID: <20170919081901.GA4231@krava> References: <1505096603-215017-1-git-send-email-kan.liang@intel.com> <20170918085708.GC17203@krava> <20170918130100.GF14469@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170918130100.GF14469@kernel.org> User-Agent: Mutt/1.9.0 (2017-09-02) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 19 Sep 2017 08:19:04 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1609 Lines: 41 On Mon, Sep 18, 2017 at 10:01:00AM -0300, Arnaldo Carvalho de Melo wrote: > Em Mon, Sep 18, 2017 at 10:57:08AM +0200, Jiri Olsa escreveu: > > On Sun, Sep 10, 2017 at 07:23:13PM -0700, kan.liang@intel.com wrote: > > > From: Kan Liang > > > > > > The patch series intends to fix the severe performance issue in > > > Knights Landing/Mill, when monitoring in heavy load system. > > > perf top costs a few minutes to show the result, which is > > > unacceptable. > > > With the patch series applied, the latency will reduces to > > > several seconds. > > > > > > machine__synthesize_threads and perf_top__mmap_read costs most of > > > the perf top time (> 99%). > > > > looks like this patchset adds locking into code paths > > used by other single threaded tools and that might > > be bad for them as noted by Andi in here: > > > > https://marc.info/?l=linux-kernel&m=149031672928989&w=2 > > > > he proposed solution and it was changed&posted by Arnaldo in here: > > > > https://marc.info/?l=linux-kernel&m=149132267410294&w=2 > > > > but looks like it never got merged > > > > could you please add this or similar code before you add the > > locking code/overhead in? > > I'm rehashing that patch and adding it on top of what is in my perf/core > branch, will push soon, for now you can take a look at tmp.perf/core. checked the code.. one nit, could we have single threaded by default? only one command is multithreaded atm, it could call perf_set_multihreaded instead of all current related commands call perf_set_singlethreaded other than that it looks ok thanks, jirka