Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754332AbbGWRHQ (ORCPT ); Thu, 23 Jul 2015 13:07:16 -0400 Received: from mail-ob0-f177.google.com ([209.85.214.177]:33554 "EHLO mail-ob0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753948AbbGWRHN (ORCPT ); Thu, 23 Jul 2015 13:07:13 -0400 From: Vince Weaver X-Google-Original-From: Vince Weaver Date: Thu, 23 Jul 2015 13:13:52 -0400 (EDT) To: "Michael Kerrisk (man-pages)" cc: linux-man@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Stephane Eranian , Alexander Shishkin , Borislav Petkov , Frederic Weisbecker , "H. Peter Anvin" , Kaixu Xia , Linus Torvalds , Mike Galbraith , Robert Richter , Thomas Gleixner , adrian.hunter@intel.com, kan.liang@intel.com, markus.t.metzger@intel.com, mathieu.poirier@linaro.org, Vince Weaver Subject: [patch 07/11] perf_event_open.2: 4.1 add AUX_FLAG_OVERWRITE support Message-ID: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2488 Lines: 67 This manpage patch relates to the addition of the AUX sample flag AUX_FLAG_OVERWRITE as added in the following commit: commit 2023a0d2829e521fe6ad6b9907f3f90bfbf57142 Author: Alexander Shishkin perf: Support overwrite mode for the AUX area Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Borislav Petkov Cc: Frederic Weisbecker Cc: H. Peter Anvin Cc: Kaixu Xia Cc: Linus Torvalds Cc: Mike Galbraith Cc: Paul Mackerras Cc: Robert Richter Cc: Stephane Eranian Cc: Thomas Gleixner Cc: acme@infradead.org Cc: adrian.hunter@intel.com Cc: kan.liang@intel.com Cc: markus.t.metzger@intel.com Cc: mathieu.poirier@linaro.org Link: http://lkml.kernel.org/r/1421237903-181015-9-git-send-email-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar Signed-off-by: Vince Weaver diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 index dfb0b64..238eb62 100644 --- a/man2/perf_event_open.2 +++ b/man2/perf_event_open.2 @@ -1670,6 +1670,15 @@ rlimit as well as the .I perf_event_mlock_kb allowance. +By default the AUX buffer will be truncated if it will not fit +in the available space in the ring buffer. +If the AUX buffer is mapped as a read only buffer, then it will +operate in ring buffer mode where old data will be overwritten +by new. +In overwrite mode it might not be possible to infer where the +new data began, and it is the consumer's job to disable +measurement while reading to avoid possible data races. + The .IR aux_head " and " aux_tail ring buffer pointers have the same behavior and ordering @@ -2476,6 +2485,10 @@ describes the aux update. .B PERF_AUX_FLAG_TRUNCATED if set then the data returned was truncated to fit the available buffer size. +.TP +.B PERF_AUX_FLAG_OVERWRITE +.\" commit 2023a0d2829e521fe6ad6b9907f3f90bfbf57142 +if set then the data returned has overwritten previous data. .RE .RE .RE -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/