Re: bad lmbench numbers for mmap

Jakub Jelinek (jj@sunsite.ms.mff.cuni.cz)
Sat, 17 Apr 1999 09:39:06 +0200 (CEST)

> Point taken. #2 means nothing would be gained. (Unless clearing a
> whole page is faster than clearing one pte at a time..)
>
> Clearing a whole page is faster on UltraSparc, because it would use
> the high speed VIS block memory stores which avoid cache pollution.
> Similar tricks could be done on the modern Pentiums...

But you know how is clear_page_tables done right now: it is reading it entry
by entry, comparing for NULL and if not NULL, freeing it/clearing.
So it is definitely much much slower.

I'll code what I postponed for 2.3 (completely fine grained page table
freeing), as I think 2.3 is close (at least I hope).

Cheers,
Jakub
___________________________________________________________________
Jakub Jelinek | jj@sunsite.mff.cuni.cz | http://sunsite.mff.cuni.cz
Administrator of SunSITE Czech Republic, MFF, Charles University
___________________________________________________________________
UltraLinux | http://ultra.linux.cz/ | http://ultra.penguin.cz/
Linux version 2.2.5 on a sparc64 machine (3958.37 BogoMips)
___________________________________________________________________

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