Re: [rfc] lockless pagecache

[Martin J. Bligh]

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

> Nick Piggin <nickpiggin@xxxxxxxxxxxx> 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.

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