Date: Tue, 8 Jul 2003 11:41:46 -0700 (PDT) From: Doug White <dwhite@gumbysoft.com> To: Andy Farkas <andyf@speednet.com.au> Cc: freebsd-current@freebsd.org Subject: Re: whats going on with the scheduler? Message-ID: <20030708113618.P25140@carver.gumbysoft.com> In-Reply-To: <20030708215553.F8850-100000@hewey.af.speednet.com.au> References: <20030708215553.F8850-100000@hewey.af.speednet.com.au>
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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.) If you don't want higher-niced processes to get their cpu time reduced when a lower-niced process starts doing work, then don't nice them. I'm sure Terry will pick this to death, buut you get the idea. I think the daemon book explains this better than I could (and with infinitely more detail). -- Doug White | FreeBSD: The Power to Serve dwhite@gumbysoft.com | www.FreeBSD.org
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