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 X-Spam-Level: X-Spam-Status: No, score=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3E41C48BE8 for ; Sat, 12 Jun 2021 23:06:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD146611C2 for ; Sat, 12 Jun 2021 23:06:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231555AbhFLXIp (ORCPT ); Sat, 12 Jun 2021 19:08:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:41192 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229753AbhFLXIo (ORCPT ); Sat, 12 Jun 2021 19:08:44 -0400 Received: from rorschach.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E991D611AD; Sat, 12 Jun 2021 23:06:42 +0000 (UTC) Date: Sat, 12 Jun 2021 19:06:41 -0400 From: Steven Rostedt To: Daniel Bristot de Oliveira Cc: linux-kernel@vger.kernel.org, Phil Auld , Sebastian Andrzej Siewior , Kate Carcia , Jonathan Corbet , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Alexandre Chartre , Clark Willaims , John Kacur , Juri Lelli , linux-doc@vger.kernel.org Subject: Re: [PATCH V3 9/9] tracing: Add timerlat tracer Message-ID: <20210612190641.4dc6dce0@rorschach.local.home> In-Reply-To: <6808245d-208c-c6d2-1c6e-7410df158992@redhat.com> References: <20210607213639.68aad064@gandalf.local.home> <20210611160340.6970e10c@gandalf.local.home> <6808245d-208c-c6d2-1c6e-7410df158992@redhat.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 12 Jun 2021 11:41:41 +0200 Daniel Bristot de Oliveira wrote: > > I think the above may be easier to understand, especially if the trace > > output that represents it is below. > > ok, I can try to capture a trace sample and represent it into the ASCII art > format above. Why capture it? Just fudge an example that fits the example ;-) > > > Also, I have to ask, shouldn't the "thread noise" really start at the > > "External clock event"? > > To go in that direction, we need to track things that delayed the IRQ execution. [snip long explanation of the obvious (to me at least) ;-) ] > the overhead is acceptable because of the sound analysis of the scheduling bound > (which is rooted in a formal specification & analysis of the system). I meant, that it needs to be documented, what the real thread noise is but due to what is available it may not be truly accurate. -- Steve