On Fri, 2009-03-27 at 10:34 +0100, Andi Kleen wrote: > Eric Anholt <e...@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. I'm assuming that that's changing. Can you explain what the "some limitations" is? (Though, of course, in a comment in mm/util.c would be better than email). -- Eric Anholt e...@anholt.net eric.anh...@intel.com
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