Re: hash table sizes

From: Andrew Morton
Date: Tue Nov 25 2003 - 16:25:45 EST


jbarnes@xxxxxxx (Jesse Barnes) wrote:
>
> On Tue, Nov 25, 2003 at 01:07:41PM -0800, Andrew Morton wrote:
> > the size of these tables dependent upon the number of dentries/inodes/etc
> > which the system is likely to support. And that does depend upon the
> > amount of direct-addressible memory.
> >
> >
> > So hum. As a starting point, what happens if we do:
> >
> > - vfs_caches_init(num_physpages);
> > + vfs_caches_init(min(num_physpages, pages_in_ZONE_NORMAL));
> >
> > ?
>
> Something like that might be ok, but on our system, all memory is in
> ZONE_DMA...
>

Well yes, we'd want

vfs_caches_init(min(num_physpages, some_platform_limit()));

which on ia32 would evaluate to nr_free_buffer_pages() and on ia64 would
evaluate to the size of one of those zones.

If the machine has zillions of small zones then perhaps this will result in
an undersized hashtable.
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