Date: Sat, 25 Jan 2003 13:58:33 -0500 (EST) From: Robert Watson <rwatson@FreeBSD.ORG> To: Steve Kargl <sgk@troutmask.apl.washington.edu> Cc: Jeff Roberson <jroberson@chesapeake.net>, Gary Jennejohn <garyj@jennejohn.org>, arch@FreeBSD.ORG Subject: Re: New scheduler Message-ID: <Pine.NEB.3.96L.1030125135459.3121B-100000@fledge.watson.org> In-Reply-To: <20030125045205.GA15091@troutmask.apl.washington.edu>
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On Fri, 24 Jan 2003, Steve Kargl wrote: > On Fri, Jan 24, 2003 at 08:47:41PM -0800, Steve Kargl wrote: > > On Fri, Jan 24, 2003 at 09:13:53PM -0500, Jeff Roberson wrote: > > > > > > > It did not help. The load averages reported be top(1) > > with the above change in palce are 7.86, 9.01, 8.72. > > Jeff, it isn't the painkillers. The 2nd sentence should read "The load > averages, reported by top(1) with the above change in place, are 7.86, > 9.01, 8.72" Part of the problem is that the load average is a poor measure of system utilization. Jeff's new scheduler may defer scheduling a process that's ready to run to improve throughput and wait for a "better" CPU to run a process on based on affinity. Potentially the result might be that the run queues are (on average) deeper, and what the load average does is measure the depth of the run queue over time. So for the moment, it's probably best to disregard load average as a measure of performance. On the other hand, actual interactivity regressions and performance changes are very relevant. Load average is intended to capture the degree of contention for CPU resources, but what exactly that means is always an interesting question. Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Network Associates Laboratories To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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