NAK, I'm wondering how often I have to reject that change. We should
probably add a comment here.
Even with a zero timeout we still need to enable signaling, otherwise
some fence will never signal if userspace just polls on them.
If a caller is only interested in the fence status without enabling the
signaling it should call dma_fence_is_signaled() instead.
Regards,
Christian.
Am 26.04.2017 um 04:50 schrieb Andres Rodriguez:
CC a few extra lists I missed.
Regards,
Andres
On 2017-04-25 09:36 PM, Andres Rodriguez wrote:
When a timeout of zero is specified, the caller is only interested in
the fence status.
In the current implementation, dma_fence_default_wait will always call
schedule_timeout() at least once for an unsignaled fence. This adds a
significant overhead to a fence status query.
Avoid this overhead by returning early if a zero timeout is specified.
Signed-off-by: Andres Rodriguez <andresx7@xxxxxxxxx>
---
This heavily affects the performance of the Source2 engine running on
radv.
This patch improves dota2(radv) perf on a i7-6700k+RX480 system from
72fps->81fps.
drivers/dma-buf/dma-fence.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 0918d3f..348e9e2 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -380,6 +380,9 @@ dma_fence_default_wait(struct dma_fence *fence,
bool intr, signed long timeout)
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
return ret;
+ if (!timeout)
+ return 0;
+
spin_lock_irqsave(fence->lock, flags);
if (intr && signal_pending(current)) {
