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clutter/frame-clock: Use single pair of maxima for render time estimate
Instead of separate pairs of short- and long-term maxima for each measured step of the frame update process. This should result in the render time estimate rising less often: Previously it did whenever the measurement of any of at least 3 out of 4 steps reached a new maximum, even if that didn't result in a new maximum for the whole update duration. Now it's only in the latter case. This should also result in a lower render time estimate (and thus input→output latency) in general, since the variability of measurements for each 3/4 steps doesn't always add up anymore. The flip side of this is that it might result in missing a display refresh cycle more often. v2: * Fix coding style in maybe_update_longterm_max_duration_us. (Robert Mader) Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3090>
This commit is contained in:
Michel Dänzer
Marge Bot
parent
c4c6d17649
commit
69afa7a142
@ -88,20 +88,12 @@ struct _ClutterFrameClock
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/* Last KMS buffer submission time. */
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int64_t last_flip_time_us;
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/* Last time we promoted short term durations to long term ones */
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/* Last time we promoted short-term maximum to long-term one */
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int64_t longterm_promotion_us;
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/* Short & long term maximum values */
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struct {
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/* Duration between desired and effective dispatch start. */
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int64_t max_dispatch_lateness_us;
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/* Duration between dispatch start and buffer swap. */
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int64_t max_dispatch_to_swap_us;
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/* Duration between buffer swap and GPU rendering finish. */
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int64_t max_swap_to_rendering_done_us;
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/* Duration between buffer swap and KMS submission. */
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int64_t max_swap_to_flip_us;
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} shortterm, longterm;
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/* Long-term maximum update duration */
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int64_t longterm_max_update_duration_us;
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/* Short-term maximum update duration */
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int64_t shortterm_max_update_duration_us;
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/* If we got new measurements last frame. */
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gboolean got_measurements_last_frame;
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@ -224,20 +216,33 @@ maybe_reschedule_update (ClutterFrameClock *frame_clock)
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}
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static void
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update_longterm_max (int64_t *longterm_max,
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int64_t *shortterm_max)
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maybe_update_longterm_max_duration_us (ClutterFrameClock *frame_clock,
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ClutterFrameInfo *frame_info)
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{
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/* Do not update long term max if there has been no measurement in over a second. */
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if (!*shortterm_max)
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/* Do not update long-term max if there has been no measurement */
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if (!frame_clock->shortterm_max_update_duration_us)
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return;
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if (*longterm_max > *shortterm_max)
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/* Exponential drop-off toward the short term max */
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*longterm_max -= (*longterm_max - *shortterm_max) / 2;
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else
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*longterm_max = *shortterm_max;
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if ((frame_info->presentation_time - frame_clock->longterm_promotion_us) <
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G_USEC_PER_SEC)
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return;
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*shortterm_max = 0;
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if (frame_clock->longterm_max_update_duration_us >
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frame_clock->shortterm_max_update_duration_us)
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{
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/* Exponential drop-off toward the short-term max */
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frame_clock->longterm_max_update_duration_us -=
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(frame_clock->longterm_max_update_duration_us -
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frame_clock->shortterm_max_update_duration_us) / 2;
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}
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else
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{
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frame_clock->longterm_max_update_duration_us =
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frame_clock->shortterm_max_update_duration_us;
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}
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frame_clock->shortterm_max_update_duration_us = 0;
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frame_clock->longterm_promotion_us = frame_info->presentation_time;
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}
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void
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@ -343,12 +348,12 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
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swap_to_rendering_done_us,
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swap_to_flip_us);
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frame_clock->shortterm.max_dispatch_to_swap_us =
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MAX (frame_clock->shortterm.max_dispatch_to_swap_us, dispatch_to_swap_us);
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frame_clock->shortterm.max_swap_to_rendering_done_us =
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MAX (frame_clock->shortterm.max_swap_to_rendering_done_us, swap_to_rendering_done_us);
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frame_clock->shortterm.max_swap_to_flip_us =
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MAX (frame_clock->shortterm.max_swap_to_flip_us, swap_to_flip_us);
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frame_clock->shortterm_max_update_duration_us =
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MAX (frame_clock->shortterm_max_update_duration_us,
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frame_clock->last_dispatch_lateness_us + dispatch_to_swap_us +
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MAX (swap_to_rendering_done_us, swap_to_flip_us));
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maybe_update_longterm_max_duration_us (frame_clock, frame_info);
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frame_clock->got_measurements_last_frame = TRUE;
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frame_clock->ever_got_measurements = TRUE;
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@ -359,20 +364,6 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
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frame_clock->last_dispatch_lateness_us);
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}
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if (frame_info->presentation_time - frame_clock->longterm_promotion_us > G_USEC_PER_SEC)
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{
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update_longterm_max (&frame_clock->longterm.max_dispatch_lateness_us,
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&frame_clock->shortterm.max_dispatch_lateness_us);
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update_longterm_max (&frame_clock->longterm.max_dispatch_to_swap_us,
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&frame_clock->shortterm.max_dispatch_to_swap_us);
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update_longterm_max (&frame_clock->longterm.max_swap_to_rendering_done_us,
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&frame_clock->shortterm.max_swap_to_rendering_done_us);
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update_longterm_max (&frame_clock->longterm.max_swap_to_flip_us,
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&frame_clock->shortterm.max_swap_to_flip_us);
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frame_clock->longterm_promotion_us = frame_info->presentation_time;
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}
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if (frame_info->refresh_rate > 1.0)
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{
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clutter_frame_clock_set_refresh_rate (frame_clock,
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@ -418,10 +409,6 @@ static int64_t
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clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock)
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{
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int64_t refresh_interval_us;
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int64_t max_dispatch_lateness_us;
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int64_t max_dispatch_to_swap_us;
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int64_t max_swap_to_rendering_done_us;
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int64_t max_swap_to_flip_us;
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int64_t max_render_time_us;
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refresh_interval_us = frame_clock->refresh_interval_us;
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@ -431,34 +418,21 @@ clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock)
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CLUTTER_DEBUG_DISABLE_DYNAMIC_MAX_RENDER_TIME))
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return refresh_interval_us * SYNC_DELAY_FALLBACK_FRACTION;
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max_dispatch_lateness_us =
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MAX (frame_clock->longterm.max_dispatch_lateness_us,
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frame_clock->shortterm.max_dispatch_lateness_us);
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max_dispatch_to_swap_us =
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MAX (frame_clock->longterm.max_dispatch_to_swap_us,
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frame_clock->shortterm.max_dispatch_to_swap_us);
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max_swap_to_rendering_done_us =
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MAX (frame_clock->longterm.max_swap_to_rendering_done_us,
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frame_clock->shortterm.max_swap_to_rendering_done_us);
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max_swap_to_flip_us =
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MAX (frame_clock->longterm.max_swap_to_flip_us,
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frame_clock->shortterm.max_swap_to_flip_us);
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/* Max render time shows how early the frame clock needs to be dispatched
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* to make it to the predicted next presentation time. It is composed of:
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* - An estimate of dispatch start lateness.
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* - An estimate of duration from dispatch start to buffer swap.
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* - Maximum between estimates of duration from buffer swap to GPU rendering
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* finish and duration from buffer swap to buffer submission to KMS. This
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* is because both of these things need to happen before the vblank, and
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* they are done in parallel.
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* - Duration of the vblank.
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* to make it to the predicted next presentation time. It is an estimate of
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* the total update duration, which is composed of:
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* - Dispatch start lateness.
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* - The duration from dispatch start to buffer swap.
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* - The maximum of duration from buffer swap to GPU rendering finish and
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* duration from buffer swap to buffer submission to KMS. This is because
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* both of these things need to happen before the vblank, and they are done
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* in parallel.
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* - The duration of vertical blank.
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* - A constant to account for variations in the above estimates.
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*/
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max_render_time_us =
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max_dispatch_lateness_us +
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max_dispatch_to_swap_us +
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MAX (max_swap_to_rendering_done_us, max_swap_to_flip_us) +
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MAX (frame_clock->longterm_max_update_duration_us,
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frame_clock->shortterm_max_update_duration_us) +
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frame_clock->vblank_duration_us +
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clutter_max_render_time_constant_us;
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@ -764,10 +738,6 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
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else
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frame_clock->last_dispatch_lateness_us = lateness_us;
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frame_clock->shortterm.max_dispatch_lateness_us =
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MAX (frame_clock->shortterm.max_dispatch_lateness_us,
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frame_clock->last_dispatch_lateness_us);
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if (G_UNLIKELY (CLUTTER_HAS_DEBUG (FRAME_TIMINGS)))
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{
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int64_t dispatch_interval_us, jitter_us;
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@ -873,10 +843,7 @@ clutter_frame_clock_record_flip_time (ClutterFrameClock *frame_clock,
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GString *
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clutter_frame_clock_get_max_render_time_debug_info (ClutterFrameClock *frame_clock)
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{
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int64_t max_dispatch_lateness_us;
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int64_t max_dispatch_to_swap_us;
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int64_t max_swap_to_rendering_done_us;
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int64_t max_swap_to_flip_us;
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int64_t max_update_duration_us;
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GString *string;
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string = g_string_new (NULL);
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@ -888,29 +855,14 @@ clutter_frame_clock_get_max_render_time_debug_info (ClutterFrameClock *frame_clo
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else
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g_string_append_printf (string, " (no measurements last frame)");
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max_dispatch_lateness_us =
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MAX (frame_clock->longterm.max_dispatch_lateness_us,
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frame_clock->shortterm.max_dispatch_lateness_us);
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max_dispatch_to_swap_us =
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MAX (frame_clock->longterm.max_dispatch_to_swap_us,
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frame_clock->shortterm.max_dispatch_to_swap_us);
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max_swap_to_rendering_done_us =
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MAX (frame_clock->longterm.max_swap_to_rendering_done_us,
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frame_clock->shortterm.max_swap_to_rendering_done_us);
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max_swap_to_flip_us =
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MAX (frame_clock->longterm.max_swap_to_flip_us,
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frame_clock->shortterm.max_swap_to_flip_us);
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max_update_duration_us =
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MAX (frame_clock->longterm_max_update_duration_us,
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frame_clock->shortterm_max_update_duration_us);
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g_string_append_printf (string, "\nVblank duration: %ld µs +",
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frame_clock->vblank_duration_us);
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g_string_append_printf (string, "\nDispatch lateness: %ld µs +",
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max_dispatch_lateness_us);
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g_string_append_printf (string, "\nDispatch to swap: %ld µs +",
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max_dispatch_to_swap_us);
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g_string_append_printf (string, "\nmax(Swap to rendering done: %ld µs,",
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max_swap_to_rendering_done_us);
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g_string_append_printf (string, "\nSwap to flip: %ld µs) +",
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max_swap_to_flip_us);
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g_string_append_printf (string, "\nUpdate duration: %ld µs +",
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max_update_duration_us);
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g_string_append_printf (string, "\nConstant: %d µs",
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clutter_max_render_time_constant_us);
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