Re: [patch] minimal page-LRU

[Ingo Molnar <mingo@chiara.csoma.elte.hu>]

On Wed, 4 Aug 1999, Andrea Arcangeli wrote:

> I did only a little not interesting benchmark. I compiled the kernel with
> 2.3.12 and 2.3.12-LRU and these are the numbers:
> 
> 2.3.12:
> real    3m0.974s
> user    3m22.400s
> sys     0m16.350s
> 
> 2.3.12-lru:
> real    2m58.483s
> user    3m23.350s
> sys     0m15.920s
> 
> NOTE: I have 128mbyte of ram so the kernel almost fit in cache during the
> compile and there isn't high I/O activity so I didn't ever expected such
> two seconds improvement...

even two seconds can be statistical noise (eg. look at the user-time
numbers, those increased by one second.). But it's not so hard to test
high-intensity VM with kernel compiles. This method is from Davem: compile
the kernel with 'make -jN', where N = 1,2,3... increasingly. [also put
'make -jN' into the top Makefile.] Sometimes at N=6 or so you'll fall out
of core 128M RAM. This is both a good stability and a good performance
test. You can even automate it. This way you'll see both the effect on
'normal' (cached) and 'high load' (swapping) situations. Such a list of
numbers is a much more reliable measurement of performance than just one
arbitrary number.

-- mingo

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