[Intel-gfx] [PATCH] drm/i915: Batch copy_from_user for relocation processing

[Daniel Vetter]

On Sat, Mar 24, 2012 at 08:12:53PM +0000, Chris Wilson wrote:
> Originally the code tried to allocate a large enough array to perform
> the copy using vmalloc, performance wasn't great and throughput was
> improved by processing each individual relocation entry separately.
> This too is not as efficient as one would desire. A compromise would be
> to allocate a single page, or to allocate a few entries on the stack,
> and process the copy in batches. The latter gives simpler code and more
> consistent performance due to a lack of heuristic.
> 
> x11perf -copywinwin10:	n450/pnv	i3-330m		i5-2520m (cpu)
>                before: 	  249000	 785000		 1280000 (80%)
>                  page:	  264000	 896000		 1280000 (65%)
>              on-stack:	  264000	 902000		 1280000 (67%)
> 
> v2: Use 512-bytes of stack for batching rather than allocate a page.
> v3: Tidy the code slightly with more descriptive variable names
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
... and also queued up for -next, thanks for the patch.
-Daniel
-- 
Daniel Vetter
Mail: daniel at ffwll.ch
Mobile: +41 (0)79 365 57 48