From owner-cvs-src@FreeBSD.ORG Tue Feb 1 22:35:18 2005 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DA07616A4CE; Tue, 1 Feb 2005 22:35:18 +0000 (GMT) Received: from srv1.cosmo-project.de (srv1.cosmo-project.de [213.83.6.106]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0C5DF43D2D; Tue, 1 Feb 2005 22:35:18 +0000 (GMT) (envelope-from ticso@cicely12.cicely.de) Received: from cicely5.cicely.de (cicely5.cicely.de [10.1.1.7]) (authenticated bits=0)j11MZDwh038161 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=OK); Tue, 1 Feb 2005 23:35:15 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (cicely12.cicely.de [IPv6:3ffe:400:8d0:301::12]) by cicely5.cicely.de (8.12.10/8.12.10) with ESMTP id j11MY5U3014616 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 1 Feb 2005 23:34:06 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: from cicely12.cicely.de (localhost [127.0.0.1]) by cicely12.cicely.de (8.12.11/8.12.11) with ESMTP id j11MY566035157; Tue, 1 Feb 2005 23:34:05 +0100 (CET) (envelope-from ticso@cicely12.cicely.de) Received: (from ticso@localhost) by cicely12.cicely.de (8.12.11/8.12.11/Submit) id j11MY4uT035156; Tue, 1 Feb 2005 23:34:04 +0100 (CET) (envelope-from ticso) Date: Tue, 1 Feb 2005 23:34:04 +0100 From: Bernd Walter To: John Baldwin Message-ID: <20050201223403.GE31822@cicely12.cicely.de> References: <200501312307.j0VN7gxm080740@repoman.freebsd.org> <200502010649.33768.jhb@FreeBSD.org> <20050201152803.GC31822@cicely12.cicely.de> <200502011132.13288.jhb@FreeBSD.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200502011132.13288.jhb@FreeBSD.org> X-Operating-System: FreeBSD cicely12.cicely.de 5.2-CURRENT alpha User-Agent: Mutt/1.5.6i X-Spam-Status: No, hits=-4.9 required=3.0 tests=BAYES_00 autolearn=ham version=2.64 X-Spam-Report: * -4.9 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0000] X-Spam-Checker-Version: SpamAssassin 2.64 (2004-01-11) on cicely12.cicely.de cc: cvs-src@FreeBSD.org cc: Bernd Walter cc: src-committers@FreeBSD.org cc: ticso@cicely.de cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/alpha/alpha machdep.c src/sys/alpha/include cpuconf.h src/sys/alpha/pci lca.c lcareg.h X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list Reply-To: ticso@cicely.de List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 01 Feb 2005 22:35:19 -0000 On Tue, Feb 01, 2005 at 11:32:13AM -0500, John Baldwin wrote: > On Tuesday 01 February 2005 10:28 am, Bernd Walter wrote: > > Would the PAL call work for SMP systems? > > Yes, though it says that the CPU counter can slow down while it is in the > waiting state, so it seems that PAL is free to implement something just like > what you did. I'm more worried about wakeup e.g. in case of one CPU releasing a lock another is waiting for. > > AFAIK no alpha CPU has native halt support so there is not much magic > > that PAL can do for us. > > What I've found out about this case is that alpha CPUs automaticaly > > reduce power on unused parts and running just a tight loop, that works > > without memory access, for a few microsecsonds might be more efficient > > do do it ourself than calling PAL, which must be doing something > > similar. > > At least I think it is possible to reduce idle power consumption from > > the current situation either way. > > Yes, right now we buzz loop with a memory access on each iteration, we could > add a for loop that just decrements a counter to zero to the idle loop if > desired. With preemption turned on we could have the idle process not check > the run queues at all and just sit in a buzz loop. Exactly this is what I was thinking about, but wanted to do power measurements first. But my priority has more interessting stuff first - the lca code already existed for years now. -- B.Walter BWCT http://www.bwct.de bernd@bwct.de info@bwct.de