From: Chris Wilson Date: Mon, 8 Apr 2013 13:28:40 +0000 (+0100) Subject: drm/i915: Use MLC (l3$) for context objects X-Git-Tag: v3.8.13~33 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cbb83bb7bea7effffbd4097b3b355780e07f273d;p=thirdparty%2Fkernel%2Fstable.git drm/i915: Use MLC (l3$) for context objects commit 4615d4c9e27eda42c3e965f208a4b4065841498c upstream. 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 Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c index a3f06bcad551d..d8ac0a3a17434 100644 --- a/drivers/gpu/drm/i915/i915_gem_context.c +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -157,6 +157,13 @@ 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.