From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.11] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1DEHgB-0007rZ-Ht for user-mode-linux-devel@lists.sourceforge.net; Wed, 23 Mar 2005 18:02:35 -0800 Received: from fire.osdl.org ([65.172.181.4] helo=smtp.osdl.org) by sc8-sf-mx1.sourceforge.net with esmtp (TLSv1:DES-CBC3-SHA:168) (Exim 4.41) id 1DEHg9-0003Sp-W7 for user-mode-linux-devel@lists.sourceforge.net; Wed, 23 Mar 2005 18:02:35 -0800 From: Andrew Morton Subject: Re: [uml-devel] [patch 02/12] uml: cpu_relax fix Message-Id: <20050323180205.1298eb85.akpm@osdl.org> In-Reply-To: <200503240250.38153.blaisorblade@yahoo.it> References: <20050322162121.4295D2125C@zion> <4241A2C0.2050206@fujitsu-siemens.com> <200503240250.38153.blaisorblade@yahoo.it> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Wed, 23 Mar 2005 18:02:05 -0800 To: Blaisorblade Cc: user-mode-linux-devel@lists.sourceforge.net, bstroesser@fujitsu-siemens.com, jdike@addtoit.com, linux-kernel@vger.kernel.org Blaisorblade wrote: > > On Wednesday 23 March 2005 18:09, Bodo Stroesser wrote: > > blaisorblade@yahoo.it wrote: > > > Use rep_nop instead of barrier for cpu_relax, following $(SUBARCH)'s > > > doing that (i.e. i386 and x86_64). > > > > IIRC, Jeff had the idea, to use sched_yield() for this (from a discussion > > on #uml). > Hmm, makes sense, but this is to benchmark well... I remember from early > discussions on 2.6 scheduler that using sched_yield might decrease > performance (IIRC starve the calling application). yup, sched_yield() is pretty uniformly bad, and can result in heaps of starvation if the machine is busy. Best to avoid it unless you really want it, and have tested it thoroughly under many-tasks-busy workloads. ------------------------------------------------------- This SF.net email is sponsored by Microsoft Mobile & Embedded DevCon 2005 Attend MEDC 2005 May 9-12 in Vegas. Learn more about the latest Windows Embedded(r) & Windows Mobile(tm) platforms, applications & content. Register by 3/29 & save $300 http://ads.osdn.com/?ad_id=6883&alloc_id=15149&op=click _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel