lkml.org 
[lkml]   [2009]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: DRM lock ordering fix series
From
Date
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


[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2009-03-27 17:39    [W:0.087 / U:0.552 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site