From 4615d4c9e27eda42c3e965f208a4b4065841498c Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Mon, 8 Apr 2013 14:28:40 +0100 Subject: [PATCH] drm/i915: Use MLC (l3$) for context objects Enabling context support increases SwapBuffers latency by about 20% (measured on an i7-3720qm). We can offset that loss slightly by enabling faster caching for the contexts. As they are not backed by any particular cache (such as the sampler or render caches) our only option is to select the generic mid-level cache. This reduces the latency of the swap by about 5%. Oddly this effect can be observed running smokin-guns on IVB at 1280x1024: Using BLT copies for swaps: 151.67 fps Using Render copies for swaps (unpatched): 141.70 fps With contexts disabled: 150.23 fps With contexts in L3$: 150.77 fps Signed-off-by: Chris Wilson Cc: Ben Widawsky Cc: Kenneth Graunke Reviewed-by: Kenneth Graunke Signed-off-by: Daniel Vetter --- drivers/gpu/drm/i915/i915_gem_context.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c index 94d873a6cffb..a1e8ecb6adf6 100644 --- a/drivers/gpu/drm/i915/i915_gem_context.c +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -152,6 +152,13 @@ create_hw_context(struct drm_device *dev, return ERR_PTR(-ENOMEM); } + if (INTEL_INFO(dev)->gen >= 7) { + ret = i915_gem_object_set_cache_level(ctx->obj, + I915_CACHE_LLC_MLC); + if (ret) + goto err_out; + } + /* The ring associated with the context object is handled by the normal * object tracking code. We give an initial ring value simple to pass an * assertion in the context switch code. -- 2.20.1