From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752877AbdFSP1w (ORCPT ); Mon, 19 Jun 2017 11:27:52 -0400 Received: from mga04.intel.com ([192.55.52.120]:47498 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751015AbdFSP1u (ORCPT ); Mon, 19 Jun 2017 11:27:50 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.39,361,1493708400"; d="scan'208";a="869548585" Subject: Re: [PATCH v3 1/n] perf/core: addressing 4x slowdown during per-process profiling of STREAM benchmark on Intel Xeon Phi To: Mark Rutland Cc: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Alexander Shishkin , Andi Kleen , Kan Liang , Dmitri Prokhorov , Valery Cherepennikov , David Carrillo-Cisneros , Stephane Eranian , linux-kernel@vger.kernel.org References: <09226446-39b9-9bd2-d60f-b9bb947987c5@linux.intel.com> <20170615195618.GA8807@leverpostej> <07a76338-4c71-569a-d36e-7d6bcd10bd74@linux.intel.com> <20170619132652.GA3894@leverpostej> <20170619151441.GB4555@leverpostej> From: Alexey Budankov Organization: Intel Corp. Message-ID: <1aa19677-4bb9-fc6c-b06a-fda1fc655888@linux.intel.com> Date: Mon, 19 Jun 2017 18:27:17 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <20170619151441.GB4555@leverpostej> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19.06.2017 18:14, Mark Rutland wrote: > On Mon, Jun 19, 2017 at 04:37:41PM +0300, Alexey Budankov wrote: >> On 19.06.2017 16:26, Mark Rutland wrote: >>> On Mon, Jun 19, 2017 at 04:08:32PM +0300, Alexey Budankov wrote: >>>> On 16.06.2017 1:10, Alexey Budankov wrote: >>>>> On 15.06.2017 22:56, Mark Rutland wrote: >>>>>> On Thu, Jun 15, 2017 at 08:41:42PM +0300, Alexey Budankov wrote: >>>>>>> This series of patches continues v2 and addresses captured comments. >>> >>>>>>> Specifically this patch replaces pinned_groups and flexible_groups >>>>>>> lists of perf_event_context by red-black cpu indexed trees avoiding >>>>>>> data structures duplication and introducing possibility to iterate >>>>>>> event groups for a specific CPU only. >>> >>>>>> Have you thrown Vince's perf fuzzer at this? >>>>>> >>>>>> If you haven't, please do. It can be found in the fuzzer directory of: >>>>>> >>>>>> https://github.com/deater/perf_event_tests >>>>> >>>>> Accepted. >>>> >>>> I run the test suite and it revealed no additional regressions in >>>> comparison to what I have on the clean kernel. >>>> >>>> However the fuzzer constantly reports some strange stacks that are >>>> not seen on the clean kernel and I have no idea how that might be >>>> caused by the patches. >>> >>> Ok; that was the kind of thing I was concerned about. >>> >>> What you say "strange stacks", what do you mean exactly? >>> >>> I take it the kernel spewing backtraces in dmesg? >>> >>> Can you dump those? >> >> Here it is: >> >> list_del corruption. prev->next should be ffff88c2c4654010, but was >> ffff88c31eb0c020 >> [ 607.632813] ------------[ cut here ]------------ >> [ 607.632816] kernel BUG at lib/list_debug.c:53! > >> [ 607.635531] Call Trace: >> [ 607.635583] list_del_event+0x1d7/0x210 > > Given this patch changes how list_{del,add}_event() works, it's possible > that this is a new bug. > > I was going to try to test this on arm64, but I couldn't get the patch > to apply. I had a go with v4.12-rc5, tip/perf/core, and tip/perf/urgent. > > Which branch should I be using as the base? v4.12-rc4+, perf/core d0fabd1 [origin/perf/core] perf/core: Remove unused perf_cgroup_event_cgrp_time() function > > Thanks, > Mark >