Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757703AbbLBI1K (ORCPT ); Wed, 2 Dec 2015 03:27:10 -0500 Received: from szxga01-in.huawei.com ([58.251.152.64]:32013 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757685AbbLBI1I (ORCPT ); Wed, 2 Dec 2015 03:27:08 -0500 Message-ID: <565EAAFD.3000103@huawei.com> Date: Wed, 2 Dec 2015 16:25:33 +0800 From: "Wangnan (F)" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Peter Zijlstra , Yunlong Song CC: , , , , , , , , , , , , , , , Subject: Re: [PATCH] perf record: Add snapshot mode support for perf's regular events References: <1448373632-8806-1-git-send-email-yunlong.song@huawei.com> <20151125092728.GZ17308@twins.programming.kicks-ass.net> In-Reply-To: <20151125092728.GZ17308@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.111.66.109] X-CFilter-Loop: Reflected X-Mirapoint-Virus-RAPID-Raw: score=unknown(0), refid=str=0001.0A020204.565EAB4A.004D,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0, ip=0.0.0.0, so=2013-06-18 04:22:30, dmn=2013-03-21 17:37:32 X-Mirapoint-Loop-Id: eecc8d3f4324afdf4aa3b94fd1c059b8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1035 Lines: 23 Hi Peter, On 2015/11/25 17:27, Peter Zijlstra wrote: > On Tue, Nov 24, 2015 at 10:00:31PM +0800, Yunlong Song wrote: >> In our patch, we create and maintain a user space ring buffer to store >> perf's tracing info, instead of directly writing to perf.data file as >> before. In snapshot mode, only a SIGUSR2 signal can trigger perf to dump >> the tracing info currently stored in the user space ring buffer to >> perf.data file. > I would very much like to first fix the perf overwrite mode: see > lkml.kernel.org/r/20151023151205.GW11639@twins.programming.kicks-ass.net I have an idea on this problem that, is it possible to put the size of an event at the end of it when we working on overwrite mode? So we can backtrack every events without too much change to ring buffer? Thank you. -- 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/