Re: 2.3.7: where are the gains?

Richard Gooch (rgooch@atnf.csiro.au)
Wed, 23 Jun 1999 11:34:12 +1000


Ingo Molnar writes:
>
> On Tue, 22 Jun 1999, Richard Gooch wrote:
>
> > Hi, all. A quick test compiling the 2.3.7 kernel tree shows 2.3.7
> > perform slightly worse than 2.3.5 for make dep. PII 233 with IDE disc.
>
> compiling the kernel is very CPU-intensive, about 95% of the time is spent
> in user-space.
>
> nevertheless the speedup does seem to show up:
>
> > 2.3.7:
> > time make zImage
> > 291.870u 17.570s 5:14.29 98.4% 0+0k 0+0io 192480pf+0w
> ^^^^^^^
>
> > 2.3.5:
> > time make zImage
> > 291.590u 18.810s 5:14.38 98.7% 0+0k 0+0io 194125pf+0w
> ^^^^^^^
> an about 10% speedup for the kernel-only component. Considering that
> compiling the kernel is doing mostly reads (well it writes object files
> but the source is bigger, unless you compile with -g), and is accessing
> files - this is not bad at all i think.

But, DaveM said in another thread:
> One decent example of this case is a kernel build, generating all
> the .depend etc. files and then reading them back almost
> immediately.

2.3.7:
time make dep
21.950u 3.120s 0:26.90 93.1% 0+0k 0+0io 41875pf+0w

2.3.5:
time make dep
22.240u 2.800s 0:25.90 96.6% 0+0k 0+0io 42128pf+0w

So we see an increase of 11% in system time, when going from 2.3.5 to
2.3.7. But according to what DaveM said, this is a case which should
definately have benefited.

Regards,

Richard....

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