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 CCF4BC433FE for ; Tue, 10 May 2022 09:45:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239158AbiEJJti (ORCPT ); Tue, 10 May 2022 05:49:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36022 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239132AbiEJJtg (ORCPT ); Tue, 10 May 2022 05:49:36 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A424B24F2B; Tue, 10 May 2022 02:45:39 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4592C615F6; Tue, 10 May 2022 09:45:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F5FCC385C9; Tue, 10 May 2022 09:45:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652175938; bh=9H7ysJz1vVhOl+TV+4Tl6mkvRpk278sDTvbAtJBV2PU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aHeL4smZjkVsPmMX5DELT9/H1TKlCLGOU2VioqwmG65chqG0QmjODQKoVcSvejKi3 K9o6p7Hco/5r85DpZx60cia+QCaOYaclimYC96A7onLGzEOg6FJhSp00bJ83B0hl7Y wr30xVBToZdNNKz2UNfV9faYzQluC3nb8Am3H1p/q7SD9GqhpmD4NpaytY05m2lDeO 8lgz4XxFtBsnNVxBFZW+ddJW4SAqPswrt4+W1MB6nDta0DQqtkQW+wtjfV2uRyLARX IPTjbpil7xjwbvxf1ofPdId3vCfw7QTKNqJOLCAgXg7A3wacY1M0bt8J+1WX6iFQIh gVxIghiwxHrxw== From: Daniel Bristot de Oliveira To: Steven Rostedt , linux-kernel@vger.kernel.org, linux-trace-devel@vger.kernel.org Cc: Daniel Bristot de Oliveira , Juri Lelli , Ingo Molnar , Clark Williams Subject: [PATCH 2/3] tracing/timerlat: Print stacktrace in the IRQ handler if needed Date: Tue, 10 May 2022 11:45:24 +0200 Message-Id: X-Mailer: git-send-email 2.32.0 In-Reply-To: <2c2d9a56c0886c8402ba320de32856cbbb10c2bb.1652175637.git.bristot@kernel.org> References: <2c2d9a56c0886c8402ba320de32856cbbb10c2bb.1652175637.git.bristot@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If print_stack and stop_tracing_us are set, and stop_tracing_us is hit with latency higher than or equal to print_stack, print the stack at the IRQ handler as it is useful to define the root cause for the IRQ latency. Cc: Steven Rostedt Cc: Ingo Molnar Signed-off-by: Daniel Bristot de Oliveira --- Documentation/trace/timerlat-tracer.rst | 5 +++-- kernel/trace/trace_osnoise.c | 13 +++++++++++++ 2 files changed, 16 insertions(+), 2 deletions(-) diff --git a/Documentation/trace/timerlat-tracer.rst b/Documentation/trace/timerlat-tracer.rst index 64d1fe6e9b93..d643c95c01eb 100644 --- a/Documentation/trace/timerlat-tracer.rst +++ b/Documentation/trace/timerlat-tracer.rst @@ -74,8 +74,9 @@ directory. The timerlat configs are: - stop_tracing_total_us: stop the system tracing if a timer latency at the *thread* context is higher than the configured value happens. Writing 0 disables this option. - - print_stack: save the stack of the IRQ occurrence, and print - it after the *thread context* event". + - print_stack: save the stack of the IRQ occurrence. The stack is printed + after the *thread context* event, or at the IRQ handler if *stop_tracing_us* + is hit. timerlat and osnoise ---------------------------- diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c index 6494ca27ea6f..9b204ee3c6f5 100644 --- a/kernel/trace/trace_osnoise.c +++ b/kernel/trace/trace_osnoise.c @@ -1580,6 +1580,19 @@ static enum hrtimer_restart timerlat_irq(struct hrtimer *timer) if (osnoise_data.stop_tracing) { if (time_to_us(diff) >= osnoise_data.stop_tracing) { + + /* + * At this point, if stop_tracing is set and <= print_stack, + * print_stack is set and would be printed in the thread handler. + * + * Thus, print the stack trace as it is helpful to define the + * root cause of an IRQ latency. + */ + if (osnoise_data.stop_tracing <= osnoise_data.print_stack) { + timerlat_save_stack(0); + timerlat_dump_stack(time_to_us(diff)); + } + osnoise_stop_tracing(); notify_new_max_latency(diff); } -- 2.32.0