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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 CA184C43461 for ; Thu, 10 Sep 2020 12:41:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77F6420BED for ; Thu, 10 Sep 2020 12:41:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599741669; bh=d23ElutQoLsVdLLOs3nz6q2kPUfQWTA4Z/VuhTPRCNE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=mG4MlzjRYyNouIDJpLAAuLHWSTumKzJ7TlQKKapq6j8OTnyBDx2m/Q4U5xv0n/hb+ rNiP3A52B43DH/rCTEKlxWy+8d5InImGdKTydZyry8KyzRWH3TR981iVLms36J768R W61ETq9YkUpIgmM7FHnywzSBeRZYdqXXyy7iZsXE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730665AbgIJMlF (ORCPT ); Thu, 10 Sep 2020 08:41:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:58378 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730654AbgIJMkL (ORCPT ); Thu, 10 Sep 2020 08:40:11 -0400 Received: from localhost.localdomain (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 28F9A21D90; Thu, 10 Sep 2020 12:39:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1599741570; bh=d23ElutQoLsVdLLOs3nz6q2kPUfQWTA4Z/VuhTPRCNE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W1KeAjvxnrUSt8kuM5CyHb8jFIS0ciUzBq+pN9QmrkxPyIQamcVeUt2Na+NAwNC0R CEGxK0Xk+eve9aoen6RUnr7aFcvg+AekAQzd9Abnx4LYOJ4sahiaBTskdJRhjTg8Li 3wImoC1wjDfQnwAyTleW6ylxmnWBNlLies1iBKho= From: Masami Hiramatsu To: Steven Rostedt , Jonathan Corbet Cc: mhiramat@kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Randy Dunlap , Ingo Molnar Subject: [PATCH 6/6] Documentation: tracing: Add the startup timing of boot-time tracing Date: Thu, 10 Sep 2020 21:39:27 +0900 Message-Id: <159974156678.478751.10215894815285734481.stgit@devnote2> X-Mailer: git-send-email 2.25.1 In-Reply-To: <159974150897.478751.17933810682730471522.stgit@devnote2> References: <159974150897.478751.17933810682730471522.stgit@devnote2> User-Agent: StGit/0.19 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org Add the note about when to start the boot-time tracing. This will be needed for the people who wants to trace earlier boot sequence. Signed-off-by: Masami Hiramatsu --- Documentation/trace/boottime-trace.rst | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/Documentation/trace/boottime-trace.rst b/Documentation/trace/boottime-trace.rst index c216f5695ae2..3931b43f902c 100644 --- a/Documentation/trace/boottime-trace.rst +++ b/Documentation/trace/boottime-trace.rst @@ -120,6 +120,20 @@ instance node, but those are also visible from other instances. So please take care for event name conflict. +When to Start +============= + +All boot-time tracing options starting with ``ftrace`` will be enabled at the +end of core_initcall. This means you can trace the events from postcore_initcall. +Most of the subsystems and architecture dependent drivers will be initialized +after that (arch_initcall or subsys_initcall). Thus, you can trace those with +boot-time tracing. +If you want to trace events before core_initcall, you can use the options +starting with ``kernel``. Some of them will be enabled eariler than the initcall +processing (for example,. ``kernel.ftrace=function`` and ``kernel.trace_event`` +will start before the initcall.) + + Examples ========