Re: Lockless page cache test results

[Nick Piggin]

Jens Axboe wrote:

> Things look pretty bad for the lockless kernel though, Nick any idea
> what is going on there? The splice change is pretty simple, see the top
> three patches here:

Could just be the use of spin lock instead of read lock.

I don't think it would be hard to convert find_get_pages_contig
to be lockless.

Patched vanilla numbers look nicer, but I'm curious as to why
__do_page_cache was so bad before, if the file was in cache.
Presumably it should not more than double tree_lock acquisition...
it isn't getting called multiple times for each page, is it?

--
SUSE Labs, Novell Inc.
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