From owner-freebsd-current@FreeBSD.ORG Mon Dec 12 19:16:07 2011 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3CBC11065677; Mon, 12 Dec 2011 19:16:07 +0000 (UTC) (envelope-from lambert@lambertfam.org) Received: from sysmon.tcworks.net (sysmon.tcworks.net [65.66.76.4]) by mx1.freebsd.org (Postfix) with ESMTP id B16A08FC1E; Mon, 12 Dec 2011 19:16:06 +0000 (UTC) Received: from sysmon.tcworks.net (localhost [127.0.0.1]) by sysmon.tcworks.net (8.13.1/8.13.1) with ESMTP id pBCJ3Ua5079662; Mon, 12 Dec 2011 13:03:30 -0600 (CST) (envelope-from lambert@lambertfam.org) Received: (from lambert@localhost) by sysmon.tcworks.net (8.13.1/8.13.1/Submit) id pBCJ3UQl079661; Mon, 12 Dec 2011 13:03:30 -0600 (CST) (envelope-from lambert@lambertfam.org) X-Authentication-Warning: sysmon.tcworks.net: lambert set sender to lambert@lambertfam.org using -f Date: Mon, 12 Dec 2011 13:03:30 -0600 From: Scott Lambert To: Current FreeBSD , freebsd-stable@freebsd.org, freebsd-performance@freebsd.org Message-ID: <20111212190330.GA69380@sysmon.tcworks.net> Mail-Followup-To: Current FreeBSD , freebsd-stable@freebsd.org, freebsd-performance@freebsd.org References: <4EE1EAFE.3070408@m5p.com> <4EE22421.9060707@gmail.com> <4EE6060D.5060201@mail.zedat.fu-berlin.de> <20111212155159.GB73597@troutmask.apl.washington.edu> <4EE6295B.3020308@cran.org.uk> <20111212170604.GA74044@troutmask.apl.washington.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111212170604.GA74044@troutmask.apl.washington.edu> User-Agent: Mutt/1.4.2.2i Cc: Subject: Re: SCHED_ULE should not be the default 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, 12 Dec 2011 19:16:07 -0000 On Mon, Dec 12, 2011 at 09:06:04AM -0800, Steve Kargl wrote: > Tuning kern.sched.preempt_thresh did not seem to help for > my workload. My code is a classic master-slave OpenMPI > application where the master runs on one node and all > cpu-bound slaves are sent to a second node. If I send > send ncpu+1 jobs to the 2nd node with ncpu's, then > ncpu-1 jobs are assigned to the 1st ncpu-1 cpus. The > last two jobs are assigned to the ncpu'th cpu, and > these ping-pong on the this cpu. AFAICT, it is a cpu > affinity issue, where ULE is trying to keep each job > associated with its initially assigned cpu. > > While one might suggest that starting ncpu+1 jobs > is not prudent, my example is just that. It is an > example showing that ULE has performance issues. > So, I now can start only ncpu jobs on each node > in the cluster and send emails to all other users > to not use those node, or use 4BSD and not worry > about loading issues. Does it meet your expectations if you start (j modulo ncpu) = 0 jobs on a node? -- Scott Lambert KC5MLE Unix SysAdmin lambert@lambertfam.org