Re: [PATCH 2.5.69.bk9] Fix reference counts for pages (take 1) [was RE: condvar wakeups]

[Saurabh Desai <sdesai austin ibm com>]

"Perez-Gonzalez, Inaky" wrote:
> This is the first take at it; I still didn't have time to test it
> (0.37 building, slow) ... but I don't think I screwed up anything
> - Saurabh, would you mind torturing it a little bit in your x4 to
> make sure it is not leaking memory anywhere? Performance wise it
> should do nothing to the system ...
> 

This patch cause about 30% slowdown with or without requeue NPTL.
And I found out why, you didn't return from __pin_page() as before
(for the fastpath). It should be like (in __pin_page()),
+       if (likely(page != NULL))
+               return __pin_page_atomic(page);

With this, it works as before. I think its costing little bit for
unpin/pin in the requeue case, which is required anyway.

- Saurabh