Messages in this thread | ![/](/images/icornerl.gif) | | Date | Thu, 27 Apr 2006 10:36:17 +0200 | From | Jens Axboe <> | Subject | Re: Lockless page cache test results |
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On Thu, Apr 27 2006, Nick Piggin wrote: > 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.
Ah, certainly, it's not lockless like find_get_page(). Care to do such a patch?
> 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?
It still does a lot of extra work that's completely wasted. With page_cache_readahead(), we should hit the RA_FLAG_INCACHE flag and be done with it.
-- Jens Axboe
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