From patchwork Tue Aug 1 09:01:18 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ze Gao X-Patchwork-Id: 13336023 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 BD3F8C001E0 for ; Tue, 1 Aug 2023 09:01:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230026AbjHAJBi (ORCPT ); Tue, 1 Aug 2023 05:01:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230372AbjHAJBh (ORCPT ); Tue, 1 Aug 2023 05:01:37 -0400 Received: from mail-pg1-x52e.google.com (mail-pg1-x52e.google.com [IPv6:2607:f8b0:4864:20::52e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A8511724; Tue, 1 Aug 2023 02:01:33 -0700 (PDT) Received: by mail-pg1-x52e.google.com with SMTP id 41be03b00d2f7-563de62f861so3209487a12.1; Tue, 01 Aug 2023 02:01:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1690880493; x=1691485293; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=HlJW6u1sZOpuT6avef9gnRgQCJ0eGQk1LzPcuYEotVk=; b=UkLe+vQfHPi6Wc95/4hjftuk9iRk0jhNEqE3orIUoIVTRtaq15v09ltRjCB54SdA72 /gIQuQe2oD1/LUYD24wcG47jUuUX+NRG46UQ+Y5vh+WF4CbgcEfaOtGrOXC3cYZPuTBx 9OBrnOABp0paIPvr3GSYR5flJvHO/Wlal9m498QMG/gb96gPv3bjon/eqEAqmCSRpuEi YDjJCE/cLf1By1SUpt5/z7anXxpm0pzPZDmj2imFyCXZgps3CAvXMReQuvj1HAZ4jGw+ 6vnkHg3/KLATxw7y4SuX18pCcfZPMwp745oUhzSHHP1O0LsIoXi1bVxGexeELj89Fw34 D+bQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690880493; x=1691485293; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=HlJW6u1sZOpuT6avef9gnRgQCJ0eGQk1LzPcuYEotVk=; b=SklzSp5u27uy5l3TK7SCddnXujAm3q+oXjokgTfLk27fX3OecsXfOnzGoLij8Mpm8L BQsWk3WbcvSoVoPuGcLQTobeMSakJXUw/OYYlkCl+Z45f8Tkj3swhbKdiFtbBhQ2jAFl +AxL1A0jX353MOBna1bvXFEeF92th+Opdh/EiD2oKWaPlbj6He1HH2s/A63zZeILUu5X uesx6juhljQggchk31wezibxUNKMJ5OEUKNIMDhvbEf0YatVV6aA7T648kx/RREAHAjR 6t8I+mpx7zbNuXqVDPccyTAf/uTtMuePLO5/6vZt3ikElQO1cPqeSWXglirunBU9G6q9 E8fw== X-Gm-Message-State: ABy/qLZh6nvaNqHEqmgEDSGN8UMk3/8KDKJHY+6/W8+qw0PT9ZpHCKLr HrbUZ9pMcKatP/UC4UBxd58= X-Google-Smtp-Source: APBJJlF29a/YZq0gOiHwz58dkyP7GeqsFipTwefGHmApUHrxK1n3p3/gbYCZjjmiNXXWcJhV+gmQSg== X-Received: by 2002:a17:90b:f10:b0:268:b0b:a084 with SMTP id br16-20020a17090b0f1000b002680b0ba084mr10823169pjb.46.1690880492742; Tue, 01 Aug 2023 02:01:32 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.20]) by smtp.googlemail.com with ESMTPSA id x34-20020a17090a6c2500b00264044cca0fsm1592523pjj.1.2023.08.01.02.01.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Aug 2023 02:01:32 -0700 (PDT) From: Ze Gao X-Google-Original-From: Ze Gao To: Adrian Hunter , Alexander Shishkin , Arnaldo Carvalho de Melo , Ian Rogers , Ingo Molnar , Jiri Olsa , Mark Rutland , Masami Hiramatsu , Namhyung Kim , Peter Zijlstra , Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org, Ze Gao Subject: [RFC PATCH v3 0/6] add to report task state in symbolic chars from sched tracepoint Date: Tue, 1 Aug 2023 17:01:18 +0800 Message-Id: <20230801090124.8050-1-zegao@tencent.com> X-Mailer: git-send-email 2.40.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org This is the 3rd attempt to fix the report task state issue in sched tracepint, you can check out previous discussions here: v1: https://lore.kernel.org/linux-trace-kernel/20230725072254.32045-1-zegao@tencent.com v2: https://lore.kernel.org/linux-trace-kernel/20230726121618.19198-1-zegao@tencent.com FYI, this series are designed not to break anything now and still do the 1-1 correspondence int-char mapping for each distinct task state we want to report, and thus will not lose any details intended for debug purposes. Of course, this might be compromised because of bugs introduced due to my stupidity. So your sage comments are very important and appreciated! diff from v2: 1. reorder to condense sched_switch record structure 2. fallback to older method to maintain backward compatibility for perf/libtraceevent 3. split housekeeping work into separate ones for readability --- In the status quo, we should see three different outcomes of the reported sched-out task state from perf-script, perf-sched-timehist, and Tp_printk of tracepoint sched_switch. And it's not hard to figure out that the former two are built upon the third one, and the reason why we see this inconsistency is that the former two does not catch up with the internal change of reported task state definitions as the kernel evolves. IMHO, exporting internal representations of task state in the tracepoint sched_switch is not a good practice and not encouraged at all, which can easily break userspace tools that relies on it. Especially when tracepoints are massively used in many observability tools nowadays due to its stable nature, which makes them no longer used for debug only purpose and we should be careful to decide what ought to be reported to userspace and what ought not. Therefore, to fix the issues mentioned above for good, I proposed to add a new variable to report task state in sched_switch with a symbolic char along with the old hardcoded value, and save the further processing of userspace tools and spare them from knowing implementation details in the kernel. After this patch seires, we report 'RSDTtXZPI' the same as in procfs, plus a 'p' which denotes PREEMP_ACTIVE and is used for sched_switch tracepoint only. Reviews welcome! Regards, Ze Ze Gao (5): perf sched: sync state char array with the kernel perf sched: reorganize sched-out task state report code sched, tracing: add to report task state in symbolic chars sched, tracing: reorganize fields of switch event struct perf sched: prefer to use prev_state_char introduced in sched_switch include/trace/events/sched.h | 68 +++++++++++++++++------------- tools/perf/builtin-sched.c | 82 ++++++++++++++++-------------------- 2 files changed, 76 insertions(+), 74 deletions(-) Ze Gao (1): libtraceevent: prefer to use prev_state_char introduced in sched_switch plugins/plugin_sched_switch.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)