From patchwork Thu Mar 19 23:22:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 1258508 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=bpf-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=goodmis.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48k33l51bmz9sSN for ; Fri, 20 Mar 2020 10:27:47 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727469AbgCSX1n (ORCPT ); Thu, 19 Mar 2020 19:27:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:36692 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727613AbgCSX1f (ORCPT ); Thu, 19 Mar 2020 19:27:35 -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 7F08C20775; Thu, 19 Mar 2020 23:27:34 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.93) (envelope-from ) id 1jF4ZZ-000hB5-Db; Thu, 19 Mar 2020 19:27:33 -0400 Message-Id: <20200319232733.286726349@goodmis.org> User-Agent: quilt/0.65 Date: Thu, 19 Mar 2020 19:22:31 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Peter Zijlstra , Masami Hiramatsu , Alexei Starovoitov , Peter Wu , Jonathan Corbet , Tom Zanussi , Shuah Khan , bpf Subject: [PATCH 12/12 v2] tracing: Have the document reflect that the trace file keeps tracing enabled References: <20200319232219.446480829@goodmis.org> MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@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 99a0890e20ec..86e76f2a40dc 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: