Messages in this thread | | | Subject | Re: DRM lock ordering fix series | From | Eric Anholt <> | Date | Fri, 27 Mar 2009 09:36:45 -0700 |
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On Fri, 2009-03-27 at 09:19 -0700, Eric Anholt wrote: > On Fri, 2009-03-27 at 10:34 +0100, Andi Kleen wrote: > > Eric Anholt <eric@anholt.net> writes: > > > > > Here's hopefully the final attempt at the lock ordering fix for GEM. The > > > problem was introduced in .29 with the GTT mapping support. We hashed out > > > a few potential fixes on the mailing list and at OSTS. Peter's plan was > > > to use get_user_pages, but it has significant CPU overhead (10% cost to text > > > rendering, though part of that is due to some dumb userland code. But it's > > > dumb userland code we're all running). > > > > > > You are aware that there is a fast path now (get_user_pages_fast) which > > is significantly faster? (but has some limitations) > > In the code I have, get_user_pages_fast is just a wrapper that calls the > get_user_pages in the way that I'm calling it from the DRM.
Ah, I see: that's a weak stub, and there is a real implementation. I didn't know we could do weak stubs.
Still, needs docs badly.
-- Eric Anholt eric@anholt.net eric.anholt@intel.com
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