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* [Intel-gfx] [PATCH 1/2] drm/i915/gt: Prefer recycling an idle fence
@ 2020-12-23 12:20 Chris Wilson
  2020-12-23 12:20 ` [Intel-gfx] [PATCH 2/2] drm/i915/gem: Optimistically prune dma-resv from the shrinker Chris Wilson
                   ` (4 more replies)
  0 siblings, 5 replies; 7+ messages in thread
From: Chris Wilson @ 2020-12-23 12:20 UTC (permalink / raw)
  To: intel-gfx; +Cc: Chris Wilson

If we want to reuse a fence that is in active use by the GPU, we have to
wait an uncertain amount of time, but if we reuse an inactive fence, we
can change it right away. Loop through the list of available fences
twice, ignoring any active fences on the first pass.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c | 22 ++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c b/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c
index 7fb36b12fe7a..a357bb431815 100644
--- a/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c
+++ b/drivers/gpu/drm/i915/gt/intel_ggtt_fencing.c
@@ -320,13 +320,31 @@ void i915_vma_revoke_fence(struct i915_vma *vma)
 		fence_write(fence);
 }
 
+static bool fence_is_active(const struct i915_fence_reg *fence)
+{
+	return fence->vma && i915_vma_is_active(fence->vma);
+}
+
 static struct i915_fence_reg *fence_find(struct i915_ggtt *ggtt)
 {
-	struct i915_fence_reg *fence;
+	struct i915_fence_reg *active = NULL;
+	struct i915_fence_reg *fence, *fn;
 
-	list_for_each_entry(fence, &ggtt->fence_list, link) {
+	list_for_each_entry_safe(fence, fn, &ggtt->fence_list, link) {
 		GEM_BUG_ON(fence->vma && fence->vma->fence != fence);
 
+		if (fence == active) /* now seen this fence twice */
+			active = ERR_PTR(-EAGAIN);
+
+		/* Prefer idle fences so we do not have to wait on the GPU */
+		if (active != ERR_PTR(-EAGAIN) && fence_is_active(fence)) {
+			if (!active)
+				active = fence;
+
+			list_move_tail(&fence->link, &ggtt->fence_list);
+			continue;
+		}
+
 		if (atomic_read(&fence->pin_count))
 			continue;
 
-- 
2.20.1

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^ permalink raw reply related	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-12-23 21:54 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-12-23 12:20 [Intel-gfx] [PATCH 1/2] drm/i915/gt: Prefer recycling an idle fence Chris Wilson
2020-12-23 12:20 ` [Intel-gfx] [PATCH 2/2] drm/i915/gem: Optimistically prune dma-resv from the shrinker Chris Wilson
2020-12-23 21:52   ` Mika Kuoppala
2020-12-23 14:55 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for series starting with [1/2] drm/i915/gt: Prefer recycling an idle fence Patchwork
2020-12-23 15:25 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2020-12-23 18:50 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
2020-12-23 21:20 ` [Intel-gfx] [PATCH 1/2] " Mika Kuoppala

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