From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C25FFC761AF for ; Thu, 30 Mar 2023 08:18:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229510AbjC3IS0 (ORCPT ); Thu, 30 Mar 2023 04:18:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229475AbjC3ISD (ORCPT ); Thu, 30 Mar 2023 04:18:03 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 81C8019B3; Thu, 30 Mar 2023 01:17:56 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 37F841FB; Thu, 30 Mar 2023 01:18:40 -0700 (PDT) Received: from [10.57.18.220] (unknown [10.57.18.220]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0318C3F73F; Thu, 30 Mar 2023 01:17:53 -0700 (PDT) Message-ID: Date: Thu, 30 Mar 2023 09:17:52 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [BUG] perf: No samples found when using kcore + coresight Content-Language: en-US To: Yang Shi Cc: Leo Yan , linux-perf-users@vger.kernel.org, LAK , coresight@lists.linaro.org, Linux Kernel Mailing List , mathieu.poirier@linaro.org, adrian.hunter@intel.com, Jiri Olsa , acme@redhat.com, mike.leach@linaro.org, Will Deacon , suzuki.poulose@arm.com, yang@os.amperecomputing.com References: <8ca2b07e-674e-afb6-ff12-87504f51f252@arm.com> <20230309113851.GF19253@leoy-yangtze.lan> <20230313121420.GB2426758@leoy-yangtze.lan> <20230314003610.GD2426758@leoy-yangtze.lan> <64db6d95-8aca-48cc-80e1-e68211922071@arm.com> From: James Clark In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org On 30/03/2023 00:25, Yang Shi wrote: > On Wed, Mar 29, 2023 at 9:08 AM James Clark wrote: >> >> >> >> On 14/03/2023 00:36, Leo Yan wrote: >>> On Mon, Mar 13, 2023 at 11:15:44AM -0700, Yang Shi wrote: >>> >>> [...] >>> >>>>> Just a quick summary, here we have two issues: >>>>> >>>>> - With command: >>>>> perf record -e cs_etm/@tmc_etf63/k --kcore --per-thread \ >>>>> -- taskset --cpu-list 1 uname", >>>>> >>>>> perf doesn't enable "text poke" attribution. >>>> >>>> No, it enables "text poke" and perf fails to decode coresight trace >>>> data too. It doesn't matter whether "--kcore" is after or before "-e >>>> cs/etm/@tmc_etf63/k". >>> >>> Understand now. Thanks for correction, if so we can ignore this one. >>> >>> Leo >> >> To me it looks like it's only --per-thread and --kcore together that >> cause the issue. I can't see if that was mentioned previously in this >> thread. > > If "--pre-thread" is not passed in, perf record failed with "failed to > mmap with 12 (Cannot allocate memory)". Sorry for not mentioning this > in the first place. I was quite focused on --kcore and didn't realize > they may be related. That's unrelated. That's because you have specified a sink and without --per-thread it tries to open the event on all cores. If the sink can't be reached from all cores it will fail to open. You can make it work without --per-thread if you limit it to a valid core like this, although I don't know which ones exactly would be valid for your system: perf record -e cs_etm/@tmc_etf63/k --kcore -C 0 \ -- taskset --cpu-list 1 uname > >> >> If it is --per-thread that's causing the issue then I think I have an >> idea why it might be. There are some assumptions and different paths >> taken in decoding in that mode that aren't correct. It causes some other >> issues to do with ordering and timestamps as well and I wanted to fix it >> previously. I wouldn't say that the text-poke change has caused a >> regression, as decoding in this mode was always a bit buggy. >> >> Maybe this is another reason to fix it properly.