0f46daa1a2
The goal here was to minimise doing any thing or any check inside the kernel that was not strictly required. For a userspace that assumes complete control over the cache domains, the kernel is usually using outdated information and may trigger clflushes where none were required. However, swapping is a situation where userspace has no knowledge of the domain transfer, and will leave the object in the CPU cache. The kernel must flush this out to the backing storage prior to use with the GPU. As we use an asynchronous task tracked by an implicit fence for this, we also need to cancel the ASYNC flag on the object so that the object will wait for the clflush to complete before being executed. This also absolves userspace of the responsibility imposed by commit77ae995789("drm/i915: Enable userspace to opt-out of implicit fencing") that its needed to ensure that the object was out of the CPU cache prior to use on the GPU. Fixes:77ae995789("drm/i915: Enable userspace to opt-out of implicit fencing") Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101571 Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Jason Ekstrand <jason@jlekstrand.net> Reviewed-by: Jason Ekstrand <jason@jlekstrand.net> Link: https://patchwork.freedesktop.org/patch/msgid/20170721145037.25105-5-chris@chris-wilson.co.uk Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
37 lines
1.4 KiB
C
37 lines
1.4 KiB
C
/*
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* Copyright © 2016 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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*/
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#ifndef __I915_GEM_CLFLUSH_H__
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#define __I915_GEM_CLFLUSH_H__
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struct drm_i915_private;
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struct drm_i915_gem_object;
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bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
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unsigned int flags);
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#define I915_CLFLUSH_FORCE BIT(0)
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#define I915_CLFLUSH_SYNC BIT(1)
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#endif /* __I915_GEM_CLFLUSH_H__ */
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