Re: [rfc] lockless pagecache

Martin J. Bligh
2005-06-27T16:37:27Z

--Andrew Morton <akpm@osdl.org> wrote (on Monday, June 27, 2005 00:46:24 -0700):

> Nick Piggin <nickpiggin@yahoo.com.au> wrote:
>>
>> First I'll put up some numbers to get you interested - of a 64-way Altix
>> with 64 processes each read-faulting in their own 512MB part of a 32GB
>> file that is preloaded in pagecache (with the proper NUMA memory
>> allocation).
>
> I bet you can get a 5x to 10x reduction in ->tree_lock traffic by doing
> 16-page faultahead.

Maybe true, but when we last tried that, faultahead sucked for performance
in a more general sense. All the extra setup and teardown cost for
unnecessary PTEs kills you, even if it's only 4 pages or so.

M.