Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753397AbZJ2ND4 (ORCPT ); Thu, 29 Oct 2009 09:03:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753297AbZJ2ND4 (ORCPT ); Thu, 29 Oct 2009 09:03:56 -0400 Received: from rcsinet11.oracle.com ([148.87.113.123]:52669 "EHLO rgminet11.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753293AbZJ2NDz (ORCPT ); Thu, 29 Oct 2009 09:03:55 -0400 Date: Thu, 29 Oct 2009 09:03:09 -0400 From: Chris Mason To: Avi Kivity Cc: Jeremy Fitzhardinge , Glauber Costa , Dan Magenheimer , Jeremy Fitzhardinge , kurt.hackel@oracle.com, the arch/x86 maintainers , Linux Kernel Mailing List , Glauber de Oliveira Costa , Xen-devel , Keir Fraser , zach.brown@oracle.com, Ingo Molnar Subject: Re: [Xen-devel] Re: [PATCH 3/5] x86/pvclock: add vsyscall implementation Message-ID: <20091029130309.GA2750@think> Mail-Followup-To: Chris Mason , Avi Kivity , Jeremy Fitzhardinge , Glauber Costa , Dan Magenheimer , Jeremy Fitzhardinge , kurt.hackel@oracle.com, the arch/x86 maintainers , Linux Kernel Mailing List , Glauber de Oliveira Costa , Xen-devel , Keir Fraser , zach.brown@oracle.com, Ingo Molnar References: <4f079cd6-0872-4cb5-832b-ee6a46841192@default> <4AE739DA.20601@goop.org> <4AE7DC04.7080706@redhat.com> <20091028092900.GG3627@mothafucka.localdomain> <4AE81011.4040904@redhat.com> <4AE883B9.4050409@goop.org> <4AE986FE.3040104@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4AE986FE.3040104@redhat.com> User-Agent: Mutt/1.5.20 (2009-06-14) X-Source-IP: acsmt355.oracle.com [141.146.40.155] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090202.4AE99292.00A2:SCFMA4539814,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 851 Lines: 19 On Thu, Oct 29, 2009 at 02:13:50PM +0200, Avi Kivity wrote: > On 10/28/2009 07:47 PM, Jeremy Fitzhardinge wrote: > >>Much better to have an API for this. Life is hacky enough already. > >My point is that if an app cares about property X then it should just > >measure property X. The fact that gettimeofday is a vsyscall is just an > >implementation detail that apps don't really care about. What they care > >about is whether gettimeofday is fast or not. > > But we can not make a reliable measurement. I can't imagine how we'd decide what fast is? Please don't make the applications guess. -chris -- 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/