Christian - it looks this patch could be merged now. Thanks, Tvrtko On 15/11/2024 10:21, Tvrtko Ursulin wrote:
From: Tvrtko Ursulin <tvrtko.ursu...@igalia.com> Testing some workloads in two different scenarios, such as games running under Gamescope on a Steam Deck, or vkcube under a Plasma desktop, shows that in a significant portion of calls the dma_fence_unwrap_merge helper is called with just a single unsignalled fence. Therefore it is worthile to add a fast path for that case and so bypass the memory allocation and insertion sort attempts. Tested scenarios: 1) Hogwarts Legacy under Gamescope ~1500 calls per second to __dma_fence_unwrap_merge. Percentages per number of fences buckets, before and after checking for signalled status, sorting and flattening: N Before After 0 0.85% 1 69.80% -> The new fast path. 2-9 29.36% 9% (Ie. 91% of this bucket flattened to 1 fence) 10-19 20-40 50+ 2) Cyberpunk 2077 under Gamescope ~2400 calls per second. N Before After 0 0.71% 1 52.53% -> The new fast path. 2-9 44.38% 50.60% (Ie. half resolved to a single fence) 10-19 2.34% 20-40 0.06% 50+ 3) vkcube under Plasma 90 calls per second. N Before After 0 1 2-9 100% 0% (Ie. all resolved to a single fence) 10-19 20-40 50+ In the case of vkcube all invocations in the 2-9 bucket were actually just two input fences. v2: * Correct local variable name and hold on to unsignaled reference. (Chistian) Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@igalia.com> Cc: Christian König <christian.koe...@amd.com> Cc: Friedrich Vock <friedrich.v...@gmx.de> --- drivers/dma-buf/dma-fence-unwrap.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c index 6345062731f1..2a059ac0ed27 100644 --- a/drivers/dma-buf/dma-fence-unwrap.c +++ b/drivers/dma-buf/dma-fence-unwrap.c @@ -84,8 +84,8 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences, struct dma_fence **fences, struct dma_fence_unwrap *iter) { + struct dma_fence *tmp, *unsignaled = NULL, **array; struct dma_fence_array *result; - struct dma_fence *tmp, **array; ktime_t timestamp; int i, j, count;@@ -94,6 +94,8 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences,for (i = 0; i < num_fences; ++i) { dma_fence_unwrap_for_each(tmp, &iter[i], fences[i]) { if (!dma_fence_is_signaled(tmp)) { + dma_fence_put(unsignaled); + unsignaled = dma_fence_get(tmp); ++count; } else { ktime_t t = dma_fence_timestamp(tmp); @@ -107,9 +109,16 @@ struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences, /* * If we couldn't find a pending fence just return a private signaled * fence with the timestamp of the last signaled one. + * + * Or if there was a single unsignaled fence left we can return it + * directly and early since that is a major path on many workloads. */ if (count == 0) return dma_fence_allocate_private_stub(timestamp); + else if (count == 1) + return unsignaled; + + dma_fence_put(unsignaled);array = kmalloc_array(count, sizeof(*array), GFP_KERNEL);if (!array)
