From patchwork Tue Jan 10 20:08:07 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Bristot de Oliveira X-Patchwork-Id: 13095629 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 4BECCC54EBC for ; Tue, 10 Jan 2023 20:09:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233303AbjAJUJA (ORCPT ); Tue, 10 Jan 2023 15:09:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59388 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233598AbjAJUIy (ORCPT ); Tue, 10 Jan 2023 15:08:54 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD79350169; Tue, 10 Jan 2023 12:08:43 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id 7ED59B819A9; Tue, 10 Jan 2023 20:08:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06A22C433D2; Tue, 10 Jan 2023 20:08:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673381321; bh=v5zZZVMVI19qPsrPgwPDLn3updtRS3vB1jiKuxNNESs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qMpchvtBibz68smIGUljQnvGDjbttteNaJGZzUsu6RXc2sn1QLZCUVdhV/Yyk/5TG uoJq2N8iTsUmKK4U/YufKfgOhRsA+uu+jqJ22GSwVIXmU+r3CgedR56/55hetmmUT6 yigtKy77jkJWqLPzvRQpJkA5vNCU1YL3YBHxnXy4pRlI2BQQhnZwV/+XKfP8TKDHgr ffn9kLSnrZhoQR44Hr795gurePRuuqr0Pqo/d3ET3IJ4eqSMDYHrn4pGpzvVKLs3ZQ tYHdv84C6jONOEdRlC8yce4bg474VqN5w0SzDCxh/GD5vkhxgrcv4synQM/mZ6suAR lPV34vq12kt3Q== From: Daniel Bristot de Oliveira To: Daniel Bristot de Oliveira , Steven Rostedt , Jonathan Corbet Cc: Juri Lelli , Clark Williams , linux-trace-devel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 6/6] Documentation/rtla: Add hwnoise man page Date: Tue, 10 Jan 2023 21:08:07 +0100 Message-Id: X-Mailer: git-send-email 2.38.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org Add a man page for the new rtla hwnoise tool, mostly based in the rtla osnoise top. Signed-off-by: Daniel Bristot de Oliveira Cc: Daniel Bristot de Oliveira Cc: Steven Rostedt Cc: Jonathan Corbet --- Documentation/tools/rtla/rtla-hwnoise.rst | 107 ++++++++++++++++++++++ 1 file changed, 107 insertions(+) create mode 100644 Documentation/tools/rtla/rtla-hwnoise.rst diff --git a/Documentation/tools/rtla/rtla-hwnoise.rst b/Documentation/tools/rtla/rtla-hwnoise.rst new file mode 100644 index 000000000000..fb1c52bbc00b --- /dev/null +++ b/Documentation/tools/rtla/rtla-hwnoise.rst @@ -0,0 +1,107 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============ +rtla-hwnoise +============ +------------------------------------------ +Detect and quantify hardware-related noise +------------------------------------------ + +:Manual section: 1 + +SYNOPSIS +======== + +**rtla hwnoise** [*OPTIONS*] + +DESCRIPTION +=========== + +**rtla hwnoise** collects the periodic summary from the *osnoise* tracer +running with *interrupts disabled*. By disabling interrupts, and the scheduling +of threads as a consequence, only non-maskable interrupts and hardware-related +noise is allowed. + +The tool also allows the configurations of the *osnoise* tracer and the +collection of the tracer output. + +OPTIONS +======= +.. include:: common_osnoise_options.rst + +.. include:: common_top_options.rst + +.. include:: common_options.rst + +EXAMPLE +======= +In the example below, the **rtla hwnoise** tool is set to run on CPUs *1-7* +on a system with 8 cores/16 threads with hyper-threading enabled. + +The tool is set to detect any noise higher than *one microsecond*, +to run for *ten minutes*, displaying a summary of the report at the +end of the session:: + + # rtla hwnoise -c 1-7 -T 1 -d 10m -q + Hardware-related Noise + duration: 0 00:10:00 | time is in us + CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI + 1 #599 599000000 138 99.99997 3 3 4 74 + 2 #599 599000000 85 99.99998 3 3 4 75 + 3 #599 599000000 86 99.99998 4 3 6 75 + 4 #599 599000000 81 99.99998 4 4 2 75 + 5 #599 599000000 85 99.99998 2 2 2 75 + 6 #599 599000000 76 99.99998 2 2 0 75 + 7 #599 599000000 77 99.99998 3 3 0 75 + + +The first column shows the *CPU*, and the second column shows how many +*Periods* the tool ran during the session. The *Runtime* is the time +the tool effectively runs on the CPU. The *Noise* column is the sum of +all noise that the tool observed, and the *% CPU Aval* is the relation +between the *Runtime* and *Noise*. + +The *Max Noise* column is the maximum hardware noise the tool detected in a +single period, and the *Max Single* is the maximum single noise seen. + +The *HW* and *NMI* columns show the total number of *hardware* and *NMI* noise +occurrence observed by the tool. + +For example, *CPU 3* ran *599* periods of *1 second Runtime*. The CPU received +*86 us* of noise during the entire execution, leaving *99.99997 %* of CPU time +for the application. In the worst single period, the CPU caused *4 us* of +noise to the application, but it was certainly caused by more than one single +noise, as the *Max Single* noise was of *3 us*. The CPU has *HW noise,* at a +rate of *six occurrences*/*ten minutes*. The CPU also has *NMIs*, at a higher +frequency: around *seven per second*. + +The tool should report *0* hardware-related noise in the ideal situation. +For example, by disabling hyper-threading to remove the hardware noise, +and disabling the TSC watchdog to remove the NMI (it is possible to identify +this using tracing options of **rtla hwnoise**), it was possible to reach +the ideal situation in the same hardware:: + + # rtla hwnoise -c 1-7 -T 1 -d 10m -q + Hardware-related Noise + duration: 0 00:10:00 | time is in us + CPU Period Runtime Noise % CPU Aval Max Noise Max Single HW NMI + 1 #599 599000000 0 100.00000 0 0 0 0 + 2 #599 599000000 0 100.00000 0 0 0 0 + 3 #599 599000000 0 100.00000 0 0 0 0 + 4 #599 599000000 0 100.00000 0 0 0 0 + 5 #599 599000000 0 100.00000 0 0 0 0 + 6 #599 599000000 0 100.00000 0 0 0 0 + 7 #599 599000000 0 100.00000 0 0 0 0 + +SEE ALSO +======== + +**rtla-osnoise**\(1) + +Osnoise tracer documentation: + +AUTHOR +====== +Written by Daniel Bristot de Oliveira + +.. include:: common_appendix.rst