vc4: Throttle outstanding rendering after submission.

Just make sure that after we've submitted, we get to at least 5
(global) submits ago before we go on to do more.  Prevents up to
seconds of lag with window movement in X with xcompmgr -c.  There may
be useful tuning to do in the future, but for now this gets us
usability.

Cc: "11.0 11.1" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Eric Anholt <eric@anholt.net>

diff --git a/src/gallium/drivers/vc4/vc4_job.c b/src/gallium/drivers/vc4/vc4_job.c
index e7b52e3..41660f6 100644 (file)
--- a/src/gallium/drivers/vc4/vc4_job.c
+++ b/src/gallium/drivers/vc4/vc4_job.c
@@ -250,6 +250,15 @@ vc4_job_submit(struct vc4_context *vc4)
                 }
         }
 
+        if (vc4->last_emit_seqno - vc4->screen->finished_seqno > 5) {
+                if (!vc4_wait_seqno(vc4->screen,
+                                    vc4->last_emit_seqno - 5,
+                                    PIPE_TIMEOUT_INFINITE,
+                                    "job throttling")) {
+                        fprintf(stderr, "Job throttling failed\n");
+                }
+        }
+
         if (vc4_debug & VC4_DEBUG_ALWAYS_SYNC) {
                 if (!vc4_wait_seqno(vc4->screen, vc4->last_emit_seqno,
                                     PIPE_TIMEOUT_INFINITE, "sync")) {