From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David S. Ahern" Subject: Re: [PATCH 1/2] perf tools: Add reference timestamp to perf header Date: Mon, 13 Dec 2010 10:49:38 -0700 Message-ID: <4D065CB2.7050104@cisco.com> References: <1291773285-16254-1-git-send-email-daahern@cisco.com> <1291773285-16254-2-git-send-email-daahern@cisco.com> <20101212201613.GA1784@nowhere> <4D06301C.2090309@cisco.com> <20101213155451.GA1691@nowhere> <20101213164854.GL5407@ghostprotocols.net> <20101213170923.GB1691@nowhere> <1292260289.6803.297.camel@twins> <20101213171537.GC1691@nowhere> <1292260699.6803.305.camel@twins> <20101213172216.GB7417@ghostprotocols.net> <1292261716.6803.332.camel@twins> <1292262433.6803.351.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from sj-iport-4.cisco.com ([171.68.10.86]:37450 "EHLO sj-iport-4.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757910Ab0LMRtk (ORCPT ); Mon, 13 Dec 2010 12:49:40 -0500 In-Reply-To: <1292262433.6803.351.camel@twins> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Peter Zijlstra Cc: Arnaldo Carvalho de Melo , Frederic Weisbecker , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org On 12/13/10 10:47, Peter Zijlstra wrote: > On Mon, 2010-12-13 at 18:35 +0100, Peter Zijlstra wrote: >> * this CLOCK_MONOTONIC offset (for what little good that does, since >> our clock isn't strictly sync'ed to CLOCK_MONOTONIC so we can incur >> arbitrary drift). > > In fact, the only sane way to do that is by creating a software counter > that represents CLOCK_MONOTONIC and sample that say once a minute (or > more often if you want smaller drift). > > What about creating a PERF_RECORD_TIME and generate an event when the counter is opened? It contains a PERF_SAMPLE_TIME and say PERF_SAMPLE_TOD (time-of-day)? We're not sending rockets to saturn; we just need the timestamps to match other log files. David