[Intel-gfx] [PATCH] drm/i915: Use hash tables for the command parser

[Volkin, Bradley D]

On Thu, May 08, 2014 at 06:42:16AM -0700, Tvrtko Ursulin wrote:
> 
> On 04/28/2014 04:22 PM, bradley.d.volkin at intel.com wrote:
> > From: Brad Volkin <bradley.d.volkin at intel.com>
> >
> > For clients that submit large batch buffers the command parser has
> > a substantial impact on performance. On my HSW ULT system performance
> > drops as much as ~20% on some tests. Most of the time is spent in the
> > command lookup code. Converting that from the current naive search to
> > a hash table lookup reduces the performance impact by as much as ~10%.
> 
> I have another question - what about register lookups, do they come up 
> in profiling as significant?

So far no. The command lookup happens for every command in every batch.
The register lookup only happens for certain commands. I think most
batches don't include such commands and those that do may only have a
few instances. Ken might have a better sense of the fequency.

Brad

> 
> Regards,
> 
> Tvrtko