[Intel-gfx] [PATCH] drm/i915: Reduce number of register access during IVB+ interrupt handling

[Chris Wilson]

On Mon, Sep 23, 2013 at 11:39:11AM -0300, Paulo Zanoni wrote:
> Also, just out of curiosity: do we get any noticeable performance
> difference on any workload? Depending on the impact I'd even vote to
> disable-by-default some of the debugging features.

The tests are typically GPU bound, we are waiting upon breadcrumb irqs
after all. So impact on total throughput is marginal (<1%), but our
interrupt routines dominant the CPU profiles, which is helped but the
unclaimed check is a really, really, slow read and still masks the
useful work.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre