From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753013AbYHPVuo (ORCPT ); Sat, 16 Aug 2008 17:50:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751354AbYHPVuh (ORCPT ); Sat, 16 Aug 2008 17:50:37 -0400 Received: from gw.goop.org ([64.81.55.164]:43918 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751062AbYHPVug (ORCPT ); Sat, 16 Aug 2008 17:50:36 -0400 Message-ID: <48A74BAA.4010908@goop.org> Date: Sat, 16 Aug 2008 14:50:34 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.16 (X11/20080723) MIME-Version: 1.0 To: Arjan van de Ven CC: Ingo Molnar , Jens Axboe , Peter Zijlstra , Christian Borntraeger , Linux Kernel Mailing List , Rusty Russell Subject: Re: [PATCH RFC 3/3] x86: use mwait for trigger API References: <48A70192.7020002@goop.org> <20080816104404.070e0c14@infradead.org> In-Reply-To: <20080816104404.070e0c14@infradead.org> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 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: > monitor/mwait is rather really expensive.. are we really sure we want > to use this? > (from an Intel cpu perspective the answer is very likely no; but I don't > know what AMD does here) > The intended use is when you're going to be waiting for a while (on the order of microseconds or more). In the Xen case, I use this to block the vcpu if we pass a few iterations without the condition being true. While the mwait patch doesn't do this at present, it could. J