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Date: Tue, 2 Mar 2004 17:18:01 -0500 (EST)
From: Robert Watson <rwatson@FreeBSD.org>
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To: Bruce Evans <bde@zeta.org.au>
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Subject: Re: buildworld times
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On Wed, 3 Mar 2004, Bruce Evans wrote:

5.2.1-GENERIC

> > >             Real            User            Sys
> > > default     2195.16         1717.69         467.78
> > > -j 2        2003.20         2151.49         539.67
> > > -j 4        1703.15         2485.99         654.00
> > > -j 6        1645.34         2595.67         718.12
> > > -j 8        1627.88         2618.15         743.53

5.2.1-ULE

> >               Real            User            Sys
> > default       2191.03         1722.31         455.82
> > -j 2          1993.30         2154.71         528.67
> > -j 4          1688.14         2493.55         646.69
> > -j 6          1630.02         2597.88         706.06
> > -j 8          1617.72         2619.99         737.98
> >
(gratuitous snipping)
> 
> > (2) If we reran these tests with 5.2-CURRENT, how would the numbers
> >     change?
> 
> I would be surprised if they changed much.  buildworld is mostly a gcc
> cpu hog benchmark, and about the only significant thing the kernel can
> do to speed up gcc is to reduce its memory contention.

Interestingly, on the same hardware using 5.2-CURRENT GENERIC - WITNESS,
INVARIANTS, et al (with ULE since that's the default now):

                Real            User            Sys
default		2304.16		1834.51		474.96         # slower
-j 2		1611.61		2715.89		684.97         # faster!
-j 4		1416.11		2988.32		878.40         # faster!
-j 6		1399.92		3090.95		955.74         # fastest!
-j 8		1405.38		3151.92		1003.69        # fasterish!

Note that this was a 5.2.1 source tree built on a 5.2-current system, so
isn't a perfect comparison.  I should have used a 5.2.1-current world
changing out only the kernel. 

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Senior Research Scientist, McAfee Research