From owner-freebsd-current@FreeBSD.ORG Tue Jul 8 15:40:44 2003 Return-Path: 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 24D4137B401; Tue, 8 Jul 2003 15:40:44 -0700 (PDT) Received: from franky.speednet.com.au (franky.speednet.com.au [203.57.65.5]) by mx1.FreeBSD.org (Postfix) with ESMTP id C7FF943F75; Tue, 8 Jul 2003 15:40:42 -0700 (PDT) (envelope-from andyf@speednet.com.au) Received: from hewey.af.speednet.com.au (hewey.af.speednet.com.au [203.38.96.242])h68Matsw036900; Wed, 9 Jul 2003 08:40:40 +1000 (EST) (envelope-from andyf@speednet.com.au) Received: from hewey.af.speednet.com.au (hewey.af.speednet.com.au [203.38.96.242])h68Mas2b011363; Wed, 9 Jul 2003 08:36:54 +1000 (EST) (envelope-from andyf@speednet.com.au) Date: Wed, 9 Jul 2003 08:36:53 +1000 (EST) From: Andy Farkas X-X-Sender: andyf@hewey.af.speednet.com.au To: Doug White In-Reply-To: <20030708113618.P25140@carver.gumbysoft.com> Message-ID: <20030709080542.H11189-100000@hewey.af.speednet.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII cc: freebsd-current@freebsd.org cc: freebsd-smp@freebsd.org Subject: Re: whats going on with the scheduler? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 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, 08 Jul 2003 22:40:44 -0000 On Tue, 8 Jul 2003, Doug White wrote: > On Tue, 8 Jul 2003, Andy Farkas wrote: > > > Any other ideas? Why would 3 (niced) cpu intensive processes suddenly get > > reduced cpu time (on a 4 cpu system) when a 4th non-resource intensive > > process gets started? > > Hm.. guess its time to explain how nice works again. > > Nice is a relative value. If you have 2 processes in a system, one with a > lower nice value (== higher "priority") than the other, the lower-niced > process will be scheduled in deference to the higher-niced process. The > scheduler attempts to ensure that niced processes are not starved. (In > practice, nice level 20 gets some special treatment.) That doesn't explain why the idle time goes up, in my case. If you have 4 processors in a box and start 3 cpu-intensive jobs, the system load will be 3.00 and idle time will be 25%. If you start another semi cpu-intensive process, one would expect the load to increase and the idle time to come down, regardless if the other 3 procs are niced or not. ps. setiathome procs run at idle level 15. -- :{ andyf@speednet.com.au Andy Farkas System Administrator Speednet Communications http://www.speednet.com.au/