From owner-cvs-all@FreeBSD.ORG Mon Oct 1 09:11:25 2007 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 4AE0316A41B; Mon, 1 Oct 2007 09:11:25 +0000 (UTC) (envelope-from jroberson@chesapeake.net) Received: from webaccess-cl.virtdom.com (webaccess-cl.virtdom.com [216.240.101.25]) by mx1.freebsd.org (Postfix) with ESMTP id DB74C13C494; Mon, 1 Oct 2007 09:11:24 +0000 (UTC) (envelope-from jroberson@chesapeake.net) Received: from [192.168.1.103] (c-67-160-44-208.hsd1.wa.comcast.net [67.160.44.208]) (authenticated bits=0) by webaccess-cl.virtdom.com (8.13.6/8.13.6) with ESMTP id l919BC6K030089 (version=TLSv1/SSLv3 cipher=DHE-DSS-AES256-SHA bits=256 verify=NO); Mon, 1 Oct 2007 05:11:14 -0400 (EDT) (envelope-from jroberson@chesapeake.net) Date: Mon, 1 Oct 2007 02:13:57 -0700 (PDT) From: Jeff Roberson X-X-Sender: jroberson@10.0.0.1 To: Bruce Evans In-Reply-To: <20071001172620.X1839@besplex.bde.org> Message-ID: <20071001020835.B583@10.0.0.1> References: <20070930040318.094E345018@ptavv.es.net> <20070930153430.U583@10.0.0.1> <20071001172620.X1839@besplex.bde.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: src-committers@freebsd.org, cvs-src@freebsd.org, Jeff Roberson , Garance A Drosehn , Ben Kaduk , cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/kern sched_ule.c X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 01 Oct 2007 09:11:25 -0000 On Mon, 1 Oct 2007, Bruce Evans wrote: > On Sun, 30 Sep 2007, Jeff Roberson wrote: > >> On Sat, 29 Sep 2007, Kevin Oberman wrote: > >>> YMMV, but ULE seems to generally work better then 4BSD for interactive >>> uniprocessor systems. The preferred scheduler for uniprocessor servers >>> is less clear, but many test have shown ULE does better for those >>> systems in the majority of cases. >> >> I feel it's safe to say desktop behavior on UP is definitely superior. > > This is unsafe to say. Given that the overwhelming amount of feedback by qualified poeple, I think it's fair to say that ULE gives a more responsive system under load. > >> I think there is no significant difference on UP between 4BSD and ULE > > This may be safe to say, but is inconsistent with the above. I meant no significant difference in performance. I'm sure there are corner case workloads in favor of one or the other. > >> except perhaps in context switching microbenchmarks where ULE falls behind. > > It is safe to say that interactive users cannot notice insignificant > differences. It takes a micro-benchmark to notice possibly-significant > differences of hundreds or even thousands of nanonseconds for context > switching. > > ULE may give higher priority to interactive processes, but most loss of > interactivity is caused by blocking on I/O, and there is nothing nothing > a scheduler can do to speed up slow or overloaded devices. There is a significant enough class of problems that benefit from the improved interactive priorities that people notice it. I have heard reports from a number of laptop users who can run at lower power levels using ULE. I am trivially able to create workloads where 4bsd falls over well before ULE. It is true that io behavior dominates in many cases but that's really a seperate issue. Jeff > > Bruce >