From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755048AbYDLUwR (ORCPT ); Sat, 12 Apr 2008 16:52:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752335AbYDLUwG (ORCPT ); Sat, 12 Apr 2008 16:52:06 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57154 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752263AbYDLUwF (ORCPT ); Sat, 12 Apr 2008 16:52:05 -0400 Message-ID: <48012002.8030701@zytor.com> Date: Sat, 12 Apr 2008 13:48:02 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: Arjan van de Ven CC: Erik Bosman , Andrew Morton , Thomas Gleixner , Ingo Molnar , Andrea Arcangeli , Linus Torvalds , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] x86: Implement prctl PR_GET_TSC and PR_SET_TSC References: <20080412124947.146865e4@laptopd505.fenrus.org> In-Reply-To: <20080412124947.146865e4@laptopd505.fenrus.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Arjan van de Ven wrote: > > Hi, > > why did you make this a configuration option? In general it's not > a good idea to make userspace visible ABI's (PR_* clearly is one of these) > a CONFIG option unless there's some HUGE space saving going on. > I don't see that here.... > > So can you explain your rationale for making this a config option? > I also saw no mention about performance impact, which need to be considered whenever *anything* is proposed to be inserted into a hot path. It may be (heck, *should be*) that the performance impact isn't measurable, but that needs to be positively established. -hpa