From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755620AbYKGFpu (ORCPT ); Fri, 7 Nov 2008 00:45:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754768AbYKGFoP (ORCPT ); Fri, 7 Nov 2008 00:44:15 -0500 Received: from smtp.polymtl.ca ([132.207.4.11]:60927 "EHLO smtp.polymtl.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754746AbYKGFoO (ORCPT ); Fri, 7 Nov 2008 00:44:14 -0500 Message-Id: <20081107052336.652868737@polymtl.ca> User-Agent: quilt/0.46-1 Date: Fri, 07 Nov 2008 00:23:36 -0500 From: Mathieu Desnoyers To: Linus Torvalds , akpm@linux-foundation.org, Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org Subject: [RFC patch 00/18] Trace Clock v2 X-Poly-FromMTA: (test.casi.polymtl.ca [132.207.72.60]) at Fri, 7 Nov 2008 05:43:22 +0000 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I've cleaned up the LTTng timestamping code, renamed it into "trace clock", ripped apart the tsc_sync.c x86 code, added documentation (printk to the console when the tracing clock is used) about what to do when an unsync TSC is detected. I however kept the cache-line bouncing workaround for now. However, I now synchronize the counters every jiffy with a per-cpu timer so it gives an upper bound to the time imprecision. The trace clock works with a trace_clock_get()/put(), so all the mechanic and overhead that might be required to provide correct timestamps on weird systems is *only* enabled when tracing is active. I plan to stick to this simple solution for now so we can get reliable tracing for 95ish% of systems out there, and to keep room for improvement (nice NTP-like schemes) for a later version. (sadly, given this is actually v2, I cannot say "let's keep that for v2") ;) This patchset applies on top of 2.6.28-rc3. Mathieu -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68