Date: Sun, 30 Nov 2003 11:06:38 -0500 (EST) From: Robert Watson <rwatson@freebsd.org> To: Colin Percival <colin.percival@wadham.ox.ac.uk> Cc: freebsd-current@freebsd.org Subject: Re: user:sys time ratio Message-ID: <Pine.NEB.3.96L.1031130110548.66375G-100000@fledge.watson.org> In-Reply-To: <5.0.2.1.1.20031130140203.031e8d08@popserver.sfu.ca>
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On Sun, 30 Nov 2003, Colin Percival wrote: > I've got a system running 5.2-BETA from 27/11/03, with the > malloc_abort, malloc_junk, DEBUG=-g, DDB, INVARIANT*, and WITNESS* > debugging options changed (as was done in 5.1-RELEASE). > When running `make buildworld`, I see large amounts of sys time; eg, > 27 minutes user & 14 minutes sys for building 5.2, or 14 minutes user & > 10 minutes sys for building 4.9. I expected the ratio of user:sys to be > much larger than this, and mailing list traffic indicates that a 4:1 > ratio is typical. (FWIW, prior to changing the debugging options, the > user:sys time ratio was around 1:1.) > Can anyone suggest why the kernel seems to be behaving so sluggishly? > > The system hardware is P4 2.8Ghz, 865G, 2GB DDR, IDE drives; there is > very little disk activity, so I'm sure that isn't the issue; and > disabling HTT results in about a 2% improvement in both user and sys > times. It sounds like you have multiple logical cores -- have you tried building a kernel without SMP support to see what happens? Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research
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