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 A2E89C4332F for ; Wed, 23 Nov 2022 17:07:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239139AbiKWRHp (ORCPT ); Wed, 23 Nov 2022 12:07:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57066 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238904AbiKWRGx (ORCPT ); Wed, 23 Nov 2022 12:06:53 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 28D69C5B51; Wed, 23 Nov 2022 09:06:44 -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 8FE3661DEC; Wed, 23 Nov 2022 17:06:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 26521C43470; Wed, 23 Nov 2022 17:06:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669223204; bh=wx38S8oDI/3l7QO5/iOpwcyoWSlY3bOo8MNcfNr6WO8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b/fagKtWUhKJtbRJor0oTXVyLiMPuyF+ekrSh4ajY32KOJCqwkQZC/WYTFXOcdI3Q kN4IbX198yi8Tej6qJYMnQoiY5WOc4l961AtInYV0qsPonyLjEqb2FVTdEHk3U1n7O AXNQU+8tJU6SLtUalujKnx85OgapVKsO8T4Mf85sH0UA8hXv6F/zn/d1qP09i1a0fA VhlaDw0PhdPgJStJWwGhtZ58OZqHGCPgMkYp0a3+hUeeBJYW1NPDqq2f7MebxwdEI3 vdf7OGZB4WR3vLchauCrRU91A4J88OLtx4+p54t8+XAhdmyx0rWm6HZkKB5YBa88/7 WxwqidzJ38sbw== From: Daniel Bristot de Oliveira To: Daniel Bristot de Oliveira , Steven Rostedt Cc: Masami Hiramatsu , Jonathan Corbet , Juri Lelli , Clark Williams , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH V2 6/6] Documentation/osnoise: Add osnoise/options documentation Date: Wed, 23 Nov 2022 18:06:24 +0100 Message-Id: X-Mailer: git-send-email 2.32.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add the documentation about the osnoise/options file, the options, and some additional explanation about the OSNOISE_WORKLOAD option. Cc: Daniel Bristot de Oliveira Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: Jonathan Corbet Signed-off-by: Daniel Bristot de Oliveira --- Documentation/trace/osnoise-tracer.rst | 32 ++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) diff --git a/Documentation/trace/osnoise-tracer.rst b/Documentation/trace/osnoise-tracer.rst index 963def9f97c6..618bcdc90bb6 100644 --- a/Documentation/trace/osnoise-tracer.rst +++ b/Documentation/trace/osnoise-tracer.rst @@ -92,8 +92,8 @@ Note that the example above shows a high number of HW noise samples. The reason being is that this sample was taken on a virtual machine, and the host interference is detected as a hardware interference. -Tracer options ---------------------- +Tracer Configuration +-------------------- The tracer has a set of options inside the osnoise directory, they are: @@ -109,6 +109,27 @@ The tracer has a set of options inside the osnoise directory, they are: - tracing_threshold: the minimum delta between two time() reads to be considered as noise, in us. When set to 0, the default value will be used, which is currently 5 us. + - osnoise/options: a set of on/off options that can be enabled by + writing the option name to the file or disabled by writing the option + name preceded with the 'NO_' prefix. For example, writing + NO_OSNOISE_WORKLOAD disables the OSNOISE_WORKLOAD option. The + special DEAFAULTS option resets all options to the default value. + +Tracer Options +-------------- + +The osnoise/options file exposes a set of on/off configuration options for +the osnoise tracer. These options are: + + - DEFAULTS: reset the options to the default value. + - OSNOISE_WORKLOAD: do not dispatch osnoise workload (see dedicated + section below). + - PANIC_ON_STOP: call panic() if the tracer stops. This option serves to + capture a vmcore. + - OSNOISE_PREEMPT_DISABLE: disable preemption while running the osnoise + workload, allowing only IRQ-related and hardware-related noise. + - OSNOISE_IRQ_DISABLE: disable IRQs while running the osnoise workload, + allowing only NMIs and hardware-related noise, like hwlat tracer. Additional Tracing ------------------ @@ -150,3 +171,10 @@ tracepoints is smaller than eight us reported in the sample_threshold. The reason roots in the overhead of the entry and exit code that happens before and after any interference execution. This justifies the dual approach: measuring thread and tracing. + +Running osnoise tracer without workload +--------------------------------------- + +By enabling the osnoise tracer with the NO_OSNOISE_WORKLOAD option set, +the osnoise: tracepoints serves to measure the execution time of +any type of Linux task, free from the interference of other tasks. -- 2.32.0