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authorMichel Dänzer <michel.daenzer@amd.com>2016-08-17 17:02:04 +0900
committerMichel Dänzer <michel@daenzer.net>2016-08-25 17:40:24 +0900
commit1e3218bc5ba2b739261f0c0bacf4eb662d377236 (patch)
treedf2bafb0fa4687640c7ad3c10d3b74d61014d2b9
parent2301705dee6324634520559b27ac6728ebb02191 (diff)
loader/dri3: Overhaul dri3_update_num_back
Always use 3 buffers when flipping. With only 2 buffers, we have to wait for a flip to complete (which takes non-0 time even with asynchronous flips) before we can start working on the next frame. We were previously only using 2 buffers for flipping if the X server supports asynchronous flips, even when we're not using asynchronous flips. This could result in bad performance (the referenced bug report is an extreme case, where the inter-frame stalls were preventing the GPU from reaching its maximum clocks). I couldn't measure any performance boost using 4 buffers with flipping. Performance actually seemed to go down slightly, but that might have been just noise. Without flipping, a single back buffer is enough for swap interval 0, but we need to use 2 back buffers when the swap interval is non-0, otherwise we have to wait for the swap interval to pass before we can start working on the next frame. This condition was previously reversed. Cc: "12.0 11.2" <mesa-stable@lists.freedesktop.org> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97260 Reviewed-by: Frank Binns <frank.binns@imgtec.com> Reviewed-by: Eric Anholt <eric@anholt.net>
-rw-r--r--src/loader/loader_dri3_helper.c15
1 files changed, 6 insertions, 9 deletions
diff --git a/src/loader/loader_dri3_helper.c b/src/loader/loader_dri3_helper.c
index e9fb97bfaf7..86ae5aecd5f 100644
--- a/src/loader/loader_dri3_helper.c
+++ b/src/loader/loader_dri3_helper.c
@@ -68,15 +68,12 @@ dri3_fence_await(xcb_connection_t *c, struct loader_dri3_buffer *buffer)
static void
dri3_update_num_back(struct loader_dri3_drawable *draw)
{
- draw->num_back = 1;
- if (draw->flipping) {
- if (!draw->is_pixmap &&
- !(draw->present_capabilities & XCB_PRESENT_CAPABILITY_ASYNC))
- draw->num_back++;
- draw->num_back++;
- }
- if (draw->vtable->get_swap_interval(draw) == 0)
- draw->num_back++;
+ if (draw->flipping)
+ draw->num_back = 3;
+ else if (draw->vtable->get_swap_interval(draw) != 0)
+ draw->num_back = 2;
+ else
+ draw->num_back = 1;
}
void