From nobody Thu Sep 11 15:23:50 2025 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 2C8ACC61DA4 for ; Sat, 18 Feb 2023 20:19:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229597AbjBRUTz (ORCPT ); Sat, 18 Feb 2023 15:19:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229660AbjBRUTj (ORCPT ); Sat, 18 Feb 2023 15:19:39 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 471821498B for ; Sat, 18 Feb 2023 12:19:36 -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 dfw.source.kernel.org (Postfix) with ESMTPS id C1FE660BEA for ; Sat, 18 Feb 2023 20:19:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90D30C43446; Sat, 18 Feb 2023 20:19:34 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.96) (envelope-from ) id 1pTTgD-000xw7-1z; Sat, 18 Feb 2023 15:19:33 -0500 Message-ID: <20230218201933.431917261@goodmis.org> User-Agent: quilt/0.66 Date: Sat, 18 Feb 2023 15:18:29 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Andrew Morton , Daniel Bristot de Oliveira , Bagas Sanjaya , Juri Lelli , Clark Williams , Jonathan Corbet Subject: [for-next][PATCH 8/8] Documentation/rtla: Add hwnoise man page References: <20230218201821.938318263@goodmis.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Daniel Bristot de Oliveira Add a man page for the new rtla hwnoise tool, mostly based in the rtla osnoise top. Link: https://lkml.kernel.org/r/27088e0f42a6129e9b75f789d78adff4171f2e79.16= 75805361.git.bristot@kernel.org Signed-off-by: Daniel Bristot de Oliveira Reviewed-by: Bagas Sanjaya Cc: Daniel Bristot de Oliveira Cc: Juri Lelli Cc: Clark Williams Cc: Jonathan Corbet Signed-off-by: Steven Rostedt (Google) --- Documentation/tools/rtla/index.rst | 1 + Documentation/tools/rtla/rtla-hwnoise.rst | 107 ++++++++++++++++++++++ 2 files changed, 108 insertions(+) create mode 100644 Documentation/tools/rtla/rtla-hwnoise.rst diff --git a/Documentation/tools/rtla/index.rst b/Documentation/tools/rtla/= index.rst index 840f0bf3e803..05d2652e4072 100644 --- a/Documentation/tools/rtla/index.rst +++ b/Documentation/tools/rtla/index.rst @@ -17,6 +17,7 @@ behavior on specific hardware. rtla-timerlat rtla-timerlat-hist rtla-timerlat-top + rtla-hwnoise =20 .. only:: subproject and html =20 diff --git a/Documentation/tools/rtla/rtla-hwnoise.rst b/Documentation/tool= s/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 + +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +rtla-hwnoise +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D +------------------------------------------ +Detect and quantify hardware-related noise +------------------------------------------ + +:Manual section: 1 + +SYNOPSIS +=3D=3D=3D=3D=3D=3D=3D=3D + +**rtla hwnoise** [*OPTIONS*] + +DESCRIPTION +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +**rtla hwnoise** collects the periodic summary from the *osnoise* tracer +running with *interrupts disabled*. By disabling interrupts, and the sched= uling +of threads as a consequence, only non-maskable interrupts and hardware-rel= ated +noise is allowed. + +The tool also allows the configurations of the *osnoise* tracer and the +collection of the tracer output. + +OPTIONS +=3D=3D=3D=3D=3D=3D=3D +.. include:: common_osnoise_options.rst + +.. include:: common_top_options.rst + +.. include:: common_options.rst + +EXAMPLE +=3D=3D=3D=3D=3D=3D=3D +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 Sing= le 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* n= oise +occurrence observed by the tool. + +For example, *CPU 3* ran *599* periods of *1 second Runtime*. The CPU rece= ived +*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 sin= gle +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 hig= her +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 identi= fy +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 Sing= le 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 +=3D=3D=3D=3D=3D=3D=3D=3D + +**rtla-osnoise**\(1) + +Osnoise tracer documentation: + +AUTHOR +=3D=3D=3D=3D=3D=3D +Written by Daniel Bristot de Oliveira + +.. include:: common_appendix.rst --=20 2.39.1