From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e35.co.us.ibm.com ([32.97.110.153]:32447 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S1751833AbWCRAfK (ORCPT ); Fri, 17 Mar 2006 19:35:10 -0500 Received: from westrelay02.boulder.ibm.com (westrelay02.boulder.ibm.com [9.17.195.11]) by e35.co.us.ibm.com (8.12.11/8.12.11) with ESMTP id k2I0Z9jh016445 for ; Fri, 17 Mar 2006 19:35:09 -0500 Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by westrelay02.boulder.ibm.com (8.12.10/NCO/VER6.8) with ESMTP id k2I0WEAg219218 for ; Fri, 17 Mar 2006 17:32:14 -0700 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.12.11/8.13.3) with ESMTP id k2I0Z9ki022190 for ; Fri, 17 Mar 2006 17:35:09 -0700 Subject: Re: Request for feedback on Generic Timeofday Subsystem (B20) From: john stultz In-Reply-To: <200603091918.01155.ak@suse.de> References: <1141695346.11401.39.camel@cog.beaverton.ibm.com> <1141953314.20123.110.camel@cog.beaverton.ibm.com> <200603091918.01155.ak@suse.de> Content-Type: text/plain Date: Fri, 17 Mar 2006 16:35:07 -0800 Message-Id: <1142642108.2885.37.camel@cog.beaverton.ibm.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org To: Andi Kleen Cc: linux-arch@vger.kernel.org List-ID: On Thu, 2006-03-09 at 19:18 +0100, Andi Kleen wrote: > On Friday 10 March 2006 02:15, john stultz wrote: > > > On an x86-64 AMD server using nopmtimer/clocksource=tsc: > > mainline vs TOD > > gettimeofday(): 74.2% > > clock_gettime(CLOCK_MONOTONIC): 77.4% > > clock_gettime(CLOCK_REALTIME): 71.6% > > > > Hmmmm. I'm heading out of town for the weekend in a few moments, and I'd > > really like to re-verify those numbers, but yea, that's a 25% > > improvement. Might be too good to be true, but that should get Andi's > > attention :) > > What is clocksource=tsc? It doesn't exist on 64bit kernels. Its part of the new clocksource infrastructure, which is arch generic. > And clock_gettime uses a completely different path from gettimeofday so if they > have the same percentage your results look somewhat suspicious. Yea, It was too good to be true. I went back to confirm the numbers and realized there were config differences. Using the same config didn't give such interesting results, but I haven't had a chance to look into it any closer. I've been busy reworking the patches (watch for them later tonight) to try to achieve a more evolutionary approach as you suggested. Once I get x86-64 back up and running I'll get some more hard numbers for you to look at. Sorry for the sensationalism. :) -john