From owner-freebsd-current@FreeBSD.ORG Tue Feb 7 22:46:43 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 130B916A423; Tue, 7 Feb 2006 22:46:43 +0000 (GMT) (envelope-from gallatin@cs.duke.edu) Received: from duke.cs.duke.edu (duke.cs.duke.edu [152.3.140.1]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6577743D46; Tue, 7 Feb 2006 22:46:41 +0000 (GMT) (envelope-from gallatin@cs.duke.edu) Received: from grasshopper.cs.duke.edu (grasshopper.cs.duke.edu [152.3.145.30]) by duke.cs.duke.edu (8.13.4/8.13.4) with ESMTP id k17MkdJf010284 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 7 Feb 2006 17:46:39 -0500 (EST) Received: (from gallatin@localhost) by grasshopper.cs.duke.edu (8.12.9p2/8.12.9/Submit) id k17MkYfX013982; Tue, 7 Feb 2006 17:46:34 -0500 (EST) (envelope-from gallatin) From: Andrew Gallatin MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17385.9034.309439.331530@grasshopper.cs.duke.edu> Date: Tue, 7 Feb 2006 17:46:34 -0500 (EST) To: John Baldwin In-Reply-To: <200602071730.53881.jhb@freebsd.org> References: <17379.56708.421007.613310@grasshopper.cs.duke.edu> <200602071037.05314.jhb@freebsd.org> <17385.7187.845964.182297@grasshopper.cs.duke.edu> <200602071730.53881.jhb@freebsd.org> X-Mailer: VM 6.75 under 21.1 (patch 12) "Channel Islands" XEmacs Lucid Cc: freebsd-current@freebsd.org, Andre Oppermann 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: Tue, 07 Feb 2006 22:46:43 -0000 John Baldwin writes: > On Tuesday 07 February 2006 17:15, Andrew Gallatin wrote: > > John Baldwin writes: > > > On Monday 06 February 2006 17:37, Andrew Gallatin wrote: > > > > John Baldwin writes: > > > > > 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)? > > > > > > > > > > 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). > > > > > > > > Hmm.. It seems to be on by default. Unfortunately, it does not seem > > > > to help. > > > > > > I'm not sure. > > > > One thing which really helps is disabling preemption. If I do that, > > I get 7.7Gb/sec with machdep.cpu_idle_hlt=1. This is slightly better > > than machdep.cpu_idle_hlt=0 and no PREEMPTION. > > > > BTW, net.isr.direct=1 in all testing. > > Do you have very little userland activity in this test? Essentially none. netserver just sits in a loop, reading from the socket and throwing the data away. Drew