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=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 53268C4727C for ; Tue, 22 Sep 2020 01:25:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2025520709 for ; Tue, 22 Sep 2020 01:25:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729676AbgIVBZV (ORCPT ); Mon, 21 Sep 2020 21:25:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:56646 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729585AbgIVBYy (ORCPT ); Mon, 21 Sep 2020 21:24:54 -0400 Received: from gandalf.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 CCD2A23AAA; Tue, 22 Sep 2020 01:24:53 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94) (envelope-from ) id 1kKX36-001sPa-Sc; Mon, 21 Sep 2020 21:24:52 -0400 Message-ID: <20200922012452.741485963@goodmis.org> User-Agent: quilt/0.66 Date: Mon, 21 Sep 2020 21:24:33 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Masami Hiramatsu Subject: [for-next][PATCH 19/26] Documentation: tracing: boot: Add an example of tracing function-calls References: <20200922012414.115238201@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu Add an example of tracing function calls on a specific function. Link: https://lkml.kernel.org/r/159972816669.428528.12390560334549382316.stgit@devnote2 Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- Documentation/trace/boottime-trace.rst | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/trace/boottime-trace.rst b/Documentation/trace/boottime-trace.rst index 9bc8aceb8c0a..ab3bfd67197c 100644 --- a/Documentation/trace/boottime-trace.rst +++ b/Documentation/trace/boottime-trace.rst @@ -168,6 +168,26 @@ is for tracing functions starting with "user\_", and others tracing The instance node also accepts event nodes so that each instance can customize its event tracing. +With the trigger action and kprobes, you can trace function-graph while +a function is called. For example, this will trace all function calls in +the pci_proc_init():: + + ftrace { + tracing_on = 0 + tracer = function_graph + event.kprobes { + start_event { + probes = "pci_proc_init" + actions = "traceon" + } + end_event { + probes = "pci_proc_init%return" + actions = "traceoff" + } + } + } + + This boot-time tracing also supports ftrace kernel parameters via boot config. For example, following kernel parameters:: -- 2.28.0