From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755309Ab0ESH63 (ORCPT ); Wed, 19 May 2010 03:58:29 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:35407 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755208Ab0ESH60 convert rfc822-to-8bit (ORCPT ); Wed, 19 May 2010 03:58:26 -0400 Subject: Re: [RFC PATCH 5/5] perf: Implement perf_output_addr() From: Peter Zijlstra To: Frederic Weisbecker Cc: Ingo Molnar , Paul Mackerras , Arnaldo Carvalho de Melo , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org In-Reply-To: <20100519072138.GC5704@nowhere> References: <20100518133258.000434886@chello.nl> <20100518133726.214318408@chello.nl> <20100519072138.GC5704@nowhere> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Wed, 19 May 2010 09:58:02 +0200 Message-ID: <1274255882.5605.10216.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-05-19 at 09:21 +0200, Frederic Weisbecker wrote: > I'm still not sure what you mean here by this multiplexing. Is > this about per cpu multiplexing? Suppose there's two events attached to the same tracepoint. Will you write the tracepoint twice and risk different data in each, or will you do it once and copy it into each buffer? > There is another problem. We need something like > perf_output_discard() in case the filter reject the event (which > must be filled for this check to happen). Yeah, I utterly hate that, I opted to let anything with a filter take the slow path. Not only would I have to add a discard, but I'd have to decrement the counter as well, which is a big no-no.