Re: bad lmbench numbers for mmap

Jamie Lokier (lkd@tantalophile.demon.co.uk)
Sat, 17 Apr 1999 03:11:45 +0200


David Miller wrote:
> 2) The freeing up of page tables at munmap
>
> I think #2 could be a possible culprit.
>
> Linus, did you see any performance degration of lat_mmap when you
> added the free_pgtables() stuff into 2.2.x? I think such a problem
> would trigger if lat_mmap is doing large enough mmap's and they are in
> the right place.

Speaking of which. In principle, freeing page tables should make
munmap() *faster*, because then you don't have to clear the page
tables.

I note 2.2.6-pre3 isn't doing that.

-- Jamie

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