From owner-freebsd-current@FreeBSD.ORG Mon Feb 6 20:31:55 2006 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A668E16A422; Mon, 6 Feb 2006 20:31:55 +0000 (GMT) (envelope-from jhb@freebsd.org) Received: from speedfactory.net (mail6.speedfactory.net [66.23.216.219]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3001F43D70; Mon, 6 Feb 2006 20:31:45 +0000 (GMT) (envelope-from jhb@freebsd.org) Received: from server.baldwin.cx (unverified [66.23.211.162]) by speedfactory.net (SurgeMail 3.5b3) with ESMTP id 7875113 for multiple; Mon, 06 Feb 2006 15:32:29 -0500 Received: from localhost (john@localhost [127.0.0.1]) by server.baldwin.cx (8.13.4/8.13.4) with ESMTP id k16KVfr4042445; Mon, 6 Feb 2006 15:31:42 -0500 (EST) (envelope-from jhb@freebsd.org) From: John Baldwin To: freebsd-current@freebsd.org Date: Mon, 6 Feb 2006 15:31:59 -0500 User-Agent: KMail/1.9.1 References: <17379.56708.421007.613310@grasshopper.cs.duke.edu> <43E74872.7000002@freebsd.org> <17383.42908.349070.31155@grasshopper.cs.duke.edu> In-Reply-To: <17383.42908.349070.31155@grasshopper.cs.duke.edu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200602061532.02223.jhb@freebsd.org> X-Virus-Scanned: ClamAV 0.87.1/1279/Mon Feb 6 13:10:36 2006 on server.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-1.4 required=4.2 tests=ALL_TRUSTED autolearn=failed version=3.1.0 X-Spam-Checker-Version: SpamAssassin 3.1.0 (2005-09-13) on server.baldwin.cx X-Server: High Performance Mail Server - http://surgemail.com r=1653887525 Cc: Andre Oppermann , Andrew Gallatin Subject: Re: machdep.cpu_idle_hlt and SMP perf? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 06 Feb 2006 20:31:55 -0000 On Monday 06 February 2006 14:46, Andrew Gallatin wrote: > Andre Oppermann writes: > > Andrew Gallatin wrote: > > > Why dooes machdep.cpu_idle_hlt=1 drop my 10GbE network rx > > > performance by a considerable amount (7.5Gbs -> 5.5Gbs)? > > <...> > > > This may be the same problem OpenBSD has fixed last year in the handling > > of the idle loop. From the kerneltrap posting: > > <....> > > > First commit message: > > http://marc.theaimsgroup.com/?l=openbsd-cvs&m=111692513727274&w=2 > > > > The MFC with all changes in one commit message: > > http://marc.theaimsgroup.com/?l=openbsd-cvs&m=111859519015510&w=2 > > The bug they fixes was missing interrupts by both calling APM's idle > routine, which may hlt, and hlt'ing in the idle loop itself. Since I > have no idea what acpi is doing, I got excited about this. > > Alas, it seems like this isn't it. I pointed cpu_idle_hook back to > cpu_idle_default and away from acpi_cpu_idle, but that made no > difference. You may be seeing problems because it might simply take a while for the CPU to wake up from HLT when an interrupt comes in. The 4BSD scheduler tries to do IPIs to wakeup any sleeping CPUs when it schedules a new thread, but that would add higher latency for ithreads than just preempting directly to the ithread. Oh, you have to turn that on, it's off by default (kern.sched.ipiwakeup.enabled=1). -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org