From a18711120764dd96ed2ee6a4d436c448542bad77 Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Tue, 29 Mar 2011 16:59:55 -0700 Subject: [PATCH] drm/i915: Use the LLC mode on gen6 for everything but display. Improves full-screen openarena on my laptop 20.3% +/- 4.0% (n=3) Improves 800x600 nexuiz on my laptop 12.3% +/- 0.1% (n=3) We have more room to improve with doing LLC caching for display using GFDT, and in doing LLC+MLC caching, but this was an easy performance win and incremental improvement toward those two. Signed-off-by: Eric Anholt Signed-off-by: Chris Wilson Reviewed-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index fb0538358c34..cb1f61dba5eb 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3700,7 +3700,23 @@ struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev, obj->base.write_domain = I915_GEM_DOMAIN_CPU; obj->base.read_domains = I915_GEM_DOMAIN_CPU; - obj->cache_level = I915_CACHE_NONE; + if (IS_GEN6(dev)) { + /* On Gen6, we can have the GPU use the LLC (the CPU + * cache) for about a 10% performance improvement + * compared to uncached. Graphics requests other than + * display scanout are coherent with the CPU in + * accessing this cache. This means in this mode we + * don't need to clflush on the CPU side, and on the + * GPU side we only need to flush internal caches to + * get data visible to the CPU. + * + * However, we maintain the display planes as UC, and so + * need to rebind when first used as such. + */ + obj->cache_level = I915_CACHE_LLC; + } else + obj->cache_level = I915_CACHE_NONE; + obj->base.driver_private = NULL; obj->fence_reg = I915_FENCE_REG_NONE; INIT_LIST_HEAD(&obj->mm_list); -- 2.30.2