Re: [RFC][PATCH] PM: Force GFP_NOIO during suspend/resume (was: Re: [linux-pm] Memory allocations in .suspend became very unreliable)

Oliver Neukum
2010-01-18T07:52:52Z

Am Montag, 18. Januar 2010 00:00:23 schrieb Rafael J. Wysocki:
> On Sunday 17 January 2010, Benjamin Herrenschmidt wrote:
> > On Sun, 2010-01-17 at 14:27 +0100, Rafael J. Wysocki wrote:
> ...
> > However, it's hard to deal with the case of allocations that have
> > already started waiting for IOs. It might be possible to have some VM
> > hook to make them wakeup, re-evaluate the situation and get out of that
> > code path but in any case it would be tricky.
>
> In the second version of the patch I used an rwsem that made us wait for these
> allocations to complete before we changed gfp_allowed_mask.

This will be a very, very hot semaphore. What's the impact on performance?

Regards
Oliver