[Intel-gfx] [PATCH 24/30] drm/i915: Refactor pwrite/pread to use single copy of get_user_pages

[Chris Wilson]

On Wed, 13 Apr 2011 08:59:55 -0700, Eric Anholt <eric at anholt.net> wrote:
> On Tue, 12 Apr 2011 21:31:52 +0100, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > Replace the three nearly identical copies of the code with a single
> > function. And take advantage of the opportunity to do some
> > micro-optimisation: avoid the vmalloc if at all possible and also avoid
> > dropping the lock unless we are forced to acquire the mm semaphore.
> 
> Could we get some performance numbers in patches that add code for
> performance?

For myself, this was justified by simply refactoring the common code.
However, x11perf -aa10text on pnv:
  before: 1.28 Mglyph/sec
  after:  1.45 Mglyph/sec

I have my SNB box doing a more thorough analysis of the difference for
various pwrite sizes (assuming that the likelihood of faulting is not
totally workload dependent.)
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre