From patchwork Tue Jul 25 07:22:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ze Gao X-Patchwork-Id: 13326024 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 62538C00528 for ; Tue, 25 Jul 2023 07:27:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232511AbjGYH1B (ORCPT ); Tue, 25 Jul 2023 03:27:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232507AbjGYH00 (ORCPT ); Tue, 25 Jul 2023 03:26:26 -0400 Received: from mail-pf1-x42d.google.com (mail-pf1-x42d.google.com [IPv6:2607:f8b0:4864:20::42d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE78810F8; Tue, 25 Jul 2023 00:23:09 -0700 (PDT) Received: by mail-pf1-x42d.google.com with SMTP id d2e1a72fcca58-66767d628e2so2945005b3a.2; Tue, 25 Jul 2023 00:23:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1690269789; x=1690874589; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=8jOqL9nsN3X2QdJmIGhs0fEScdnThT1mzgrts+M8u0c=; b=P3uSFiU1A85ZSJW+KDb9oGfLXAkcmTl8KJIjIHI34hO7DMh5CQ8xjVOvFCjugBnao5 YoeoJgqCFcrBpF4FPxEi9hY5p9j/Ih56nHnaMAYwHzFYN/UCT9PC/DPY2D2jFYembcJh Xl0AyJgZa/ji6U2z/EpGxkZ3iOMTsH2YsGVfd/DKUlE1G0DLQJ2B1rsMvHZi2gW7ZmIY UfLBfyTZF7h6Md2IZcbw3hu95oeKNqp/9OOVqqEOt2e7urSSFg0wHqzmskEgijgSgTPh +0dH0y109s6pCjy0eJcNgBb7u1kxRi2TU05xSiVMn/sqDvIQBMiwdjlMp/3OKqI2v98d jMFg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690269789; x=1690874589; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=8jOqL9nsN3X2QdJmIGhs0fEScdnThT1mzgrts+M8u0c=; b=ER6JJHr1sed9NOcDtF4zuZ20RzLmiO8HeEEnF3SDXEQVnbbDg7CV4ctbWBj69m2f3i lvE6Ne9kmFgmpgiMsyPAaqdLcmXGRkIP+r7rPVvKfjgvb5IrCVHNDjaDuQsx/f7kpoB2 5VTY4twQh1ccpS3bFQ02vdfgg8IkvHAetbHjneR3mbdFUMAwhpuOcRO13uiHi0OQykPw O1ljzWGDpx7lpxeiEYZKlhEXoXiEAT/dMApaafws4FB6tLWO/SqVQ9CxjlHs9/OXTbD7 R9F0B4c9YJ5TvYwZYGheq9H+xAk1LQquxUz79Ast0n8j8RamIscQL13WnTPrTmrDMZky 6kig== X-Gm-Message-State: ABy/qLacNpjrY4myBTnVgDuahanKkPcWpmUNDZtHaZfD/kgpQKz+h19s NhP3nsLuNjSEhenjrNbhkzM= X-Google-Smtp-Source: APBJJlE5P3KgIbml3rlumG2mIwCYc1q2G6bn6RD40IAKDiBVKE3ViSGYgMDvR1b5GmMw34nrbunaOw== X-Received: by 2002:a05:6a00:194c:b0:668:711a:7d93 with SMTP id s12-20020a056a00194c00b00668711a7d93mr7317580pfk.19.1690269789133; Tue, 25 Jul 2023 00:23:09 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.82]) by smtp.googlemail.com with ESMTPSA id d12-20020a63734c000000b0055acfd94c20sm9863908pgn.35.2023.07.25.00.23.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Jul 2023 00:23:08 -0700 (PDT) From: Ze Gao X-Google-Original-From: Ze Gao To: Ingo Molnar , Peter Zijlstra , Steven Rostedt , Namhyung Kim , Ian Rogers , Arnaldo Carvalho de Melo , Jiri Olsa , Mark Rutland , Masami Hiramatsu , Adrian Hunter , Alexander Shishkin Cc: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Ze Gao Subject: [RFC PATCH 1/3] sched, tracing: report task state in symbolic chars instead Date: Tue, 25 Jul 2023 15:22:52 +0800 Message-Id: <20230725072254.32045-2-zegao@tencent.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230725072254.32045-1-zegao@tencent.com> References: <20230725072254.32045-1-zegao@tencent.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org Internal representations of task state are likely to be changed or ordered, and reporting them to userspace without exporting them as part of API is not a good choice, which can easily break a userspace observability tool as kernel evolves. For example, perf suffers from this and still reports wrong states by this patch. OTOH, some masqueraded state like TASK_REPORT_IDLE and TASK_REPORT_MAX are also reported inadvertently, which confuses things even more. So report task state in symbolic char instead, which is self-explaining and no further translation is needed. Note for PREEMPT_ACTIVE, we introduce 'p' to report it and use the old conventions for the rest. Signed-off-by: Ze Gao --- include/trace/events/sched.h | 41 +++++++++++++----------------------- 1 file changed, 15 insertions(+), 26 deletions(-) diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index fbb99a61f714..51102a7c0c2d 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -6,6 +6,7 @@ #define _TRACE_SCHED_H #include +#include #include #include #include @@ -187,7 +188,7 @@ DEFINE_EVENT(sched_wakeup_template, sched_wakeup_new, TP_ARGS(p)); #ifdef CREATE_TRACE_POINTS -static inline long __trace_sched_switch_state(bool preempt, +static inline const char __trace_sched_switch_state(bool preempt, unsigned int prev_state, struct task_struct *p) { @@ -197,13 +198,6 @@ static inline long __trace_sched_switch_state(bool preempt, BUG_ON(p != current); #endif /* CONFIG_SCHED_DEBUG */ - /* - * Preemption ignores task state, therefore preempted tasks are always - * RUNNING (we will not have dequeued if state != RUNNING). - */ - if (preempt) - return TASK_REPORT_MAX; - /* * task_state_index() uses fls() and returns a value from 0-8 range. * Decrement it by 1 (except TASK_RUNNING state i.e 0) before using @@ -212,7 +206,16 @@ static inline long __trace_sched_switch_state(bool preempt, */ state = __task_state_index(prev_state, p->exit_state); - return state ? (1 << (state - 1)) : state; + /* + * Preemption ignores task state, therefore preempted tasks are always + * RUNNING (we will not have dequeued if state != RUNNING). + * Here, we use 'p' to denote this case and only for this case. + */ + if (preempt) + return 'p'; + + + return task_index_to_char(state); } #endif /* CREATE_TRACE_POINTS */ @@ -232,7 +235,7 @@ TRACE_EVENT(sched_switch, __array( char, prev_comm, TASK_COMM_LEN ) __field( pid_t, prev_pid ) __field( int, prev_prio ) - __field( long, prev_state ) + __field( char, prev_state ) __array( char, next_comm, TASK_COMM_LEN ) __field( pid_t, next_pid ) __field( int, next_prio ) @@ -249,22 +252,8 @@ TRACE_EVENT(sched_switch, /* XXX SCHED_DEADLINE */ ), - TP_printk("prev_comm=%s prev_pid=%d prev_prio=%d prev_state=%s%s ==> next_comm=%s next_pid=%d next_prio=%d", - __entry->prev_comm, __entry->prev_pid, __entry->prev_prio, - - (__entry->prev_state & (TASK_REPORT_MAX - 1)) ? - __print_flags(__entry->prev_state & (TASK_REPORT_MAX - 1), "|", - { TASK_INTERRUPTIBLE, "S" }, - { TASK_UNINTERRUPTIBLE, "D" }, - { __TASK_STOPPED, "T" }, - { __TASK_TRACED, "t" }, - { EXIT_DEAD, "X" }, - { EXIT_ZOMBIE, "Z" }, - { TASK_PARKED, "P" }, - { TASK_DEAD, "I" }) : - "R", - - __entry->prev_state & TASK_REPORT_MAX ? "+" : "", + TP_printk("prev_comm=%s prev_pid=%d prev_prio=%d prev_state=%c ==> next_comm=%s next_pid=%d next_prio=%d", + __entry->prev_comm, __entry->prev_pid, __entry->prev_prio, __entry->prev_state, __entry->next_comm, __entry->next_pid, __entry->next_prio) );