Date: Sun, 30 Nov 2003 15:38:54 +0100 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Colin Percival <colin.percival@wadham.ox.ac.uk> Cc: freebsd-current@freebsd.org Subject: Re: user:sys time ratio Message-ID: <26322.1070203134@critter.freebsd.dk> In-Reply-To: Your message of "Sun, 30 Nov 2003 14:34:37 GMT." <5.0.2.1.1.20031130143248.020dc740@popserver.sfu.ca>
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In message <5.0.2.1.1.20031130143248.020dc740@popserver.sfu.ca>, Colin Percival writes: >At 15:30 30/11/2003 +0100, Poul-Henning Kamp wrote: >>In message <5.0.2.1.1.20031130140203.031e8d08@popserver.sfu.ca>, Colin >>Percival >> writes: >> > 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. > >I've seen UNIX systems have "typical" system/user splits from 1/9 to 9/1 >>it all depends on what you're doing. > > Sure, but buildworld is a fairly well-defined benchmark; I wouldn't >expect to see such a large difference when running exactly the same code on >different systems. The amount of system time depends on a lot of environmental factors. For instance on my amd64/SMP, the vnode pool is mis-sized, so the the namecache does not reflect what is actually already in RAM. The result is a fair bit of system time wasted instantiating vnodes from cached inode diskblocks. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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