Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755904AbZGGCh6 (ORCPT ); Mon, 6 Jul 2009 22:37:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753474AbZGGCht (ORCPT ); Mon, 6 Jul 2009 22:37:49 -0400 Received: from tx2ehsobe003.messaging.microsoft.com ([65.55.88.13]:31156 "EHLO TX2EHSOBE006.bigfish.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753027AbZGGChs (ORCPT ); Mon, 6 Jul 2009 22:37:48 -0400 X-Greylist: delayed 901 seconds by postgrey-1.27 at vger.kernel.org; Mon, 06 Jul 2009 22:37:48 EDT X-SpamScore: -29 X-BigFish: VPS-29(z34a4jz1432R98dN1447R1805Mzz1202hzzz2fh6bh61h) X-Spam-TCS-SCL: 0:0 Message-ID: <4A52B155.2080000@am.sony.com> Date: Mon, 6 Jul 2009 19:22:13 -0700 From: Tim Bird User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Steven Rostedt CC: linux kernel , Frederic Weisbecker , Ingo Molnar Subject: Re: [PATCH 1/2] ftrace: Add duration filtering to function graph tracer References: <4A528769.5020200@am.sony.com> <4A52A74D.8000005@am.sony.com> In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 07 Jul 2009 02:22:14.0326 (UTC) FILETIME=[BDC14D60:01C9FEA9] X-SEL-encryption-scan: scanned Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1211 Lines: 31 Steven Rostedt wrote: > On Mon, 6 Jul 2009, Tim Bird wrote: >> Another thing I thought of was to not commit the entry event until function >> exit. I'm not sure the ring buffer supports having an entry outstanding for >> long periods of time, though. This would, I believe, hold readers at the entries for >> the last 'completed' functions, which might solve reader/writer races. > > Heh, I doubt that would be acceptable. The problem is that between reserve > and commit, we disable preemption. Thus every function (even the scheduler > itself) would have preemption disabled ;-) Doh! I think I saw that, but only had a vague recollection of it. Yeah, that would be a problem ;-) I'll give the issues some more thought, and see if I can come up with something. Thanks for the feedback. -- Tim ============================= Tim Bird Architecture Group Chair, CE Linux Forum Senior Staff Engineer, Sony Corporation of America ============================= -- 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/