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[0654/1094] drm/i915: Make contexts non-snooped on non-LLC platforms

Message ID 1413889294-31328-655-git-send-email-dheerajx.s.jamwal@intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Dheeraj Jamwal Oct. 21, 2014, 10:54 a.m. UTC 
From: Ville Syrjälä <ville.syrjala@linux.intel.com>

We don't do CPU access to GPU contexts so making the GPU access snoop
the CPU caches seems silly, and potentially expensive.

v2: Use !IS_VALLEYVIEW instead of HAS_LLC as this is really
    about what the PTEs can represent.
    Add a comment clarifying the situation.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
(cherry picked from commit ad2ac08bf34b54c99026ebe50ea275b08b5b8ca2)

Conflicts:

	drivers/gpu/drm/i915/i915_gem_context.c
Signed-off-by: Dheeraj Jamwal <dheerajx.s.jamwal@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_context.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
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Patch

diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index 45b81f8..2b25e57 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -239,8 +239,15 @@  __create_hw_context(struct drm_device *dev,
 			ret = -ENOMEM;
 			goto err_out;
 		}
-
-		if (INTEL_INFO(dev)->gen >= 7) {
+	/*
+	 * Try to make the context utilize L3 as well as LLC.
+	 *
+	 * On VLV we don't have L3 controls in the PTEs so we
+	 * shouldn't touch the cache level, especially as that
+	 * would make the object snooped which might have a
+	 * negative performance impact.
+	 */
+	if (INTEL_INFO(dev)->gen >= 7 && !IS_VALLEYVIEW(dev)) {
 			ret = i915_gem_object_set_cache_level(ctx->obj,
 							      I915_CACHE_L3_LLC);
 			/* Failure shouldn't ever happen this early */