| From 4615d4c9e27eda42c3e965f208a4b4065841498c Mon Sep 17 00:00:00 2001 |
| From: Chris Wilson <chris@chris-wilson.co.uk> |
| Date: Mon, 8 Apr 2013 14:28:40 +0100 |
| Subject: drm/i915: Use MLC (l3$) for context objects |
| |
| From: Chris Wilson <chris@chris-wilson.co.uk> |
| |
| commit 4615d4c9e27eda42c3e965f208a4b4065841498c upstream. |
| |
| Enabling context support increases SwapBuffers latency by about 20% |
| (measured on an i7-3720qm). We can offset that loss slightly by enabling |
| faster caching for the contexts. As they are not backed by any |
| particular cache (such as the sampler or render caches) our only option |
| is to select the generic mid-level cache. This reduces the latency of |
| the swap by about 5%. |
| |
| Oddly this effect can be observed running smokin-guns on IVB at |
| 1280x1024: |
| Using BLT copies for swaps: 151.67 fps |
| Using Render copies for swaps (unpatched): 141.70 fps |
| With contexts disabled: 150.23 fps |
| With contexts in L3$: 150.77 fps |
| |
| Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> |
| Cc: Ben Widawsky <ben@bwidawsk.net> |
| Cc: Kenneth Graunke <kenneth@whitecape.org> |
| Reviewed-by: Kenneth Graunke <kenneth@whitecape.org> |
| Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/gpu/drm/i915/i915_gem_context.c | 7 +++++++ |
| 1 file changed, 7 insertions(+) |
| |
| --- 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. |
