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drm/i915: Skip waking the device to service pwrite

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If the device is in runtime suspend, resuming takes time and reduces our
powersaving. If this was for a small write into an object, that resume
will take longer than any savings in using the indirect GGTT access to
avoid the cpu cache.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171019063733.31620-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson 2017-10-19 07:37:33 +01:00
parent 2f26cdc0e2
commit 8bd8181590
1 changed files with 20 additions and 3 deletions
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23
drivers/gpu/drm/i915/i915_gem.c
View file

@ -1240,7 +1240,23 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
if (ret)
return ret;
intel_runtime_pm_get(i915);
if (i915_gem_object_has_struct_page(obj)) {
/*
* Avoid waking the device up if we can fallback, as
* waking/resuming is very slow (worst-case 10-100 ms
* depending on PCI sleeps and our own resume time).
* This easily dwarfs any performance advantage from
* using the cache bypass of indirect GGTT access.
*/
if (!intel_runtime_pm_get_if_in_use(i915)) {
ret = -EFAULT;
goto out_unlock;
}
} else {
/* No backing pages, no fallback, we must force GGTT access */
intel_runtime_pm_get(i915);
}
vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0,
PIN_MAPPABLE |
PIN_NONFAULT |
@ -1257,7 +1273,7 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
if (IS_ERR(vma)) {
ret = insert_mappable_node(ggtt, &node, PAGE_SIZE);
if (ret)
goto out_unlock;
goto out_rpm;
GEM_BUG_ON(!node.allocated);
}
@ -1320,8 +1336,9 @@ i915_gem_gtt_pwrite_fast(struct drm_i915_gem_object *obj,
} else {
i915_vma_unpin(vma);
}
out_unlock:
out_rpm:
intel_runtime_pm_put(i915);
out_unlock:
mutex_unlock(&i915->drm.struct_mutex);
return ret;
}