Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754254AbcCWJRS (ORCPT ); Wed, 23 Mar 2016 05:17:18 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:37913 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753431AbcCWJRD (ORCPT ); Wed, 23 Mar 2016 05:17:03 -0400 Date: Wed, 23 Mar 2016 10:16:54 +0100 From: Peter Zijlstra To: Wang Nan Cc: mingo@redhat.com, linux-kernel@vger.kernel.org, He Kuang , Alexei Starovoitov , Arnaldo Carvalho de Melo , Brendan Gregg , Jiri Olsa , Masami Hiramatsu , Namhyung Kim , Zefan Li , pi3orama@163.com, Vince Weaver , "Michael Kerrisk (man-pages)" Subject: Re: [PATCH 1/5] perf core: Introduce new ioctl options to pause and resume ring buffer Message-ID: <20160323091654.GV6344@twins.programming.kicks-ass.net> References: <1457949585-191064-1-git-send-email-wangnan0@huawei.com> <1457949585-191064-2-git-send-email-wangnan0@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1457949585-191064-2-git-send-email-wangnan0@huawei.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1292 Lines: 29 On Mon, Mar 14, 2016 at 09:59:41AM +0000, Wang Nan wrote: > Add new ioctl() to pause/resume ring-buffer output. > > In some situations we want to read from ring buffer only when we > ensure nothing can write to the ring buffer during reading. Without > this patch we have to turn off all events attached to this ring buffer > to achieve this. > > This patch is for supporting overwrite ring buffer. Following > commits will introduce new methods support reading from overwrite ring > buffer. Before reading caller must ensure the ring buffer is frozen, or > the reading is unreliable. > diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h > index 1afe962..a3c1903 100644 > --- a/include/uapi/linux/perf_event.h > +++ b/include/uapi/linux/perf_event.h > @@ -401,6 +401,7 @@ struct perf_event_attr { > #define PERF_EVENT_IOC_SET_FILTER _IOW('$', 6, char *) > #define PERF_EVENT_IOC_ID _IOR('$', 7, __u64 *) > #define PERF_EVENT_IOC_SET_BPF _IOW('$', 8, __u32) > +#define PERF_EVENT_IOC_PAUSE_OUTPUT _IOW('$', 9, __u32) Can you also do a patch to the man-pages? http://man7.org/linux/man-pages/man2/perf_event_open.2.html Michael and Vince (who has so far been stellar in composing all that) might be able to point you to the 'right' resources for that.