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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A065C433FE for ; Fri, 15 Oct 2021 15:08:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7517261056 for ; Fri, 15 Oct 2021 15:08:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240842AbhJOPKc convert rfc822-to-8bit (ORCPT ); Fri, 15 Oct 2021 11:10:32 -0400 Received: from us-smtp-delivery-44.mimecast.com ([205.139.111.44]:45880 "EHLO us-smtp-delivery-44.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240810AbhJOPKX (ORCPT ); Fri, 15 Oct 2021 11:10:23 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-520-ylIcSVFJMIyqlON_zGhW0A-1; Fri, 15 Oct 2021 11:08:10 -0400 X-MC-Unique: ylIcSVFJMIyqlON_zGhW0A-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 62ABA802575; Fri, 15 Oct 2021 15:08:08 +0000 (UTC) Received: from x1.com (unknown [10.22.9.103]) by smtp.corp.redhat.com (Postfix) with ESMTP id 43E3A5F4E7; Fri, 15 Oct 2021 15:08:06 +0000 (UTC) From: Daniel Bristot de Oliveira To: Steven Rostedt Cc: Daniel Bristot de Oliveira , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Sebastian Andrzej Siewior , x86@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/4] tracing/doc: Fix typos on the timerlat tracer documentation Date: Fri, 15 Oct 2021 17:07:49 +0200 Message-Id: In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=bristot@kernel.org X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kernel.org Content-Transfer-Encoding: 8BIT Content-Type: text/plain; charset=WINDOWS-1252 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Fixes a series of typos in the timerlat doc. Cc: Steven Rostedt Cc: Daniel Bristot de Oliveira Cc: Jonathan Corbet Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Cc: Sebastian Andrzej Siewior Cc: x86@kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-kernel@vger.kernel.org Fixes: a955d7eac177 ("trace: Add timerlat tracer") Signed-off-by: Daniel Bristot de Oliveira --- Documentation/trace/timerlat-tracer.rst | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/Documentation/trace/timerlat-tracer.rst b/Documentation/trace/timerlat-tracer.rst index c7cbb557aee7..64d1fe6e9b93 100644 --- a/Documentation/trace/timerlat-tracer.rst +++ b/Documentation/trace/timerlat-tracer.rst @@ -3,7 +3,7 @@ Timerlat tracer ############### The timerlat tracer aims to help the preemptive kernel developers to -find souces of wakeup latencies of real-time threads. Like cyclictest, +find sources of wakeup latencies of real-time threads. Like cyclictest, the tracer sets a periodic timer that wakes up a thread. The thread then computes a *wakeup latency* value as the difference between the *current time* and the *absolute time* that the timer was set to expire. The main @@ -50,14 +50,14 @@ The second is the *timer latency* observed by the thread. The ACTIVATION ID field serves to relate the *irq* execution to its respective *thread* execution. -The *irq*/*thread* splitting is important to clarify at which context +The *irq*/*thread* splitting is important to clarify in which context the unexpected high value is coming from. The *irq* context can be -delayed by hardware related actions, such as SMIs, NMIs, IRQs -or by a thread masking interrupts. Once the timer happens, the delay +delayed by hardware-related actions, such as SMIs, NMIs, IRQs, +or by thread masking interrupts. Once the timer happens, the delay can also be influenced by blocking caused by threads. For example, by -postponing the scheduler execution via preempt_disable(), by the -scheduler execution, or by masking interrupts. Threads can -also be delayed by the interference from other threads and IRQs. +postponing the scheduler execution via preempt_disable(), scheduler +execution, or masking interrupts. Threads can also be delayed by the +interference from other threads and IRQs. Tracer options --------------------- @@ -68,14 +68,14 @@ directory. The timerlat configs are: - cpus: CPUs at which a timerlat thread will execute. - timerlat_period_us: the period of the timerlat thread. - - osnoise/stop_tracing_us: stop the system tracing if a + - stop_tracing_us: stop the system tracing if a timer latency at the *irq* context higher than the configured value happens. Writing 0 disables this option. - stop_tracing_total_us: stop the system tracing if a - timer latency at the *thread* context higher than the configured + 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 ocurrence, and print - it afte the *thread context* event". + - print_stack: save the stack of the IRQ occurrence, and print + it after the *thread context* event". timerlat and osnoise ---------------------------- @@ -95,7 +95,7 @@ For example:: timerlat/5-1035 [005] ....... 548.771104: #402268 context thread timer_latency 39960 ns In this case, the root cause of the timer latency does not point to a -single cause, but to multiple ones. Firstly, the timer IRQ was delayed +single cause but to multiple ones. Firstly, the timer IRQ was delayed for 13 us, which may point to a long IRQ disabled section (see IRQ stacktrace section). Then the timer interrupt that wakes up the timerlat thread took 7597 ns, and the qxl:21 device IRQ took 7139 ns. Finally, -- 2.31.1