Re: Patch to reorder functions in the vmlinux to a defined order

From: Linus Torvalds
Date: Thu Feb 23 2006 - 14:30:50 EST




On Thu, 23 Feb 2006, linux-os (Dick Johnson) wrote:
> >
> > Does anybody want to run benchmarks? (Totally untested, may not boot,
> > might physically accost your pets for all I know).
> >
> > Linus
>
> I just reconfigured and rebuilt linux-2.6.15.4 to put PHYSICAL_START
> at 0x00400000, unconditionally and it booted fine and is working so
> a 'boot' shouldn't be a problem.

I ended up doing even more.

For me, running lmbench with this, it seems to improve some things by up
to 20% (pipe bandwidth and latency, small file delete), some other things
by 10% (larger file delete), and others not at all.

Still, that 20% is _huge_.

HOWEVER. I didn't compare very strictly. I should have done many more runs
(I only did three), and more importantly, I should have compared the exact
same kernel (I compared the new results against a kernel that was a couple
of weeks old, so there were other differences). So it's a bit suspect.
Finally, it might depend on the core a lot, and other cores might not get
the same results.

So somebody should do a much better test. I'm too lazy.

Linus
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