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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 DC770C2D0F1 for ; Sun, 29 Mar 2020 18:43:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B4305214D8 for ; Sun, 29 Mar 2020 18:43:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728702AbgC2Snd (ORCPT ); Sun, 29 Mar 2020 14:43:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:43058 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728570AbgC2SnT (ORCPT ); Sun, 29 Mar 2020 14:43:19 -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 AB8A920BED; Sun, 29 Mar 2020 18:43:18 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.93) (envelope-from ) id 1jIctx-002Fxa-Jz; Sun, 29 Mar 2020 14:43:17 -0400 Message-Id: <20200329184317.504571083@goodmis.org> User-Agent: quilt/0.65 Date: Sun, 29 Mar 2020 14:43:06 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton Subject: [for-next][PATCH 14/21] tracing: Have the document reflect that the trace file keeps tracing enabled References: <20200329184252.289087453@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" Now that reading the trace file does not temporarly stop tracing while it is open, update the document to reflect this fact. Link: http://lkml.kernel.org/r/20200317213417.209675068@goodmis.org Signed-off-by: Steven Rostedt (VMware) --- Documentation/trace/ftrace.rst | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index c33950a35d65..00621731bf27 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -125,10 +125,13 @@ of ftrace. Here is a list of some of the key files: trace: This file holds the output of the trace in a human - readable format (described below). Note, tracing is temporarily - disabled when the file is open for reading. Once all readers - are closed, tracing is re-enabled. Opening this file for + readable format (described below). Opening this file for writing with the O_TRUNC flag clears the ring buffer content. + Note, this file is not a consumer. If tracing is off + (no tracer running, or tracing_on is zero), it will produce + the same output each time it is read. When tracing is on, + it may produce inconsistent results as it tries to read + the entire buffer without consuming it. trace_pipe: @@ -142,9 +145,7 @@ of ftrace. Here is a list of some of the key files: will not be read again with a sequential read. The "trace" file is static, and if the tracer is not adding more data, it will display the same - information every time it is read. Unlike the - "trace" file, opening this file for reading will not - temporarily disable tracing. + information every time it is read. trace_options: -- 2.25.1