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https://github.com/brl/mutter.git
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frame-clock: Simplify dynamic max render time calculation
Store only two values per kind of duration: The short term and long term maximum. The short term maximum is updated in each frame clock dispatch. The long term maximum is updated at most once per second: If the short term maximum is higher, the long term maximum is updated to match it. Otherwise, a fraction of the delta between the two maxima is subtracted from the long term maximum. Compared to the previous algorithm: * The calculcations are simpler. * The calculated max render time has a slow exponential drop-off (by at most a few milliseconds every second) instead of potentially abruptly dropping after as few as 16 frames. This should fix https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4830 since the short term maximum should always include a sample from the clock's second tick. v2: * Use divisor 2 instead of 4. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2500>
This commit is contained in:
Michel Dänzer
Marge Bot
parent
99850f4645
commit
ca341ef1ea
@ -34,17 +34,6 @@ enum
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static guint signals[N_SIGNALS];
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/* An estimate queue holds several int64_t values. Adding a new value to the
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* queue overwrites the oldest value.
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*/
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#define ESTIMATE_QUEUE_LENGTH 16
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typedef struct _EstimateQueue
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{
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int64_t values[ESTIMATE_QUEUE_LENGTH];
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int next_index;
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} EstimateQueue;
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#define SYNC_DELAY_FALLBACK_FRACTION 0.875
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typedef struct _ClutterFrameListener
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@ -97,14 +86,21 @@ 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 few durations between desired and effective dispatch start. */
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EstimateQueue dispatch_lateness_us;
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/* Last few durations between dispatch start and buffer swap. */
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EstimateQueue dispatch_to_swap_us;
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/* Last few durations between buffer swap and GPU rendering finish. */
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EstimateQueue swap_to_rendering_done_us;
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/* Last few durations between buffer swap and KMS submission. */
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EstimateQueue swap_to_flip_us;
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/* Last time we promoted short term durations to long term ones */
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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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/* If we got new measurements last frame. */
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gboolean got_measurements_last_frame;
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@ -119,14 +115,6 @@ struct _ClutterFrameClock
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G_DEFINE_TYPE (ClutterFrameClock, clutter_frame_clock,
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G_TYPE_OBJECT)
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static void
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estimate_queue_add_value (EstimateQueue *queue,
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int64_t value)
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{
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queue->values[queue->next_index] = value;
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queue->next_index = (queue->next_index + 1) % ESTIMATE_QUEUE_LENGTH;
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}
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float
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clutter_frame_clock_get_refresh_rate (ClutterFrameClock *frame_clock)
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{
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@ -227,6 +215,23 @@ maybe_reschedule_update (ClutterFrameClock *frame_clock)
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}
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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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{
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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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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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*shortterm_max = 0;
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}
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void
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clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
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ClutterFrameInfo *frame_info)
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@ -276,9 +281,6 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
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if (frame_info->presentation_time > 0)
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frame_clock->last_presentation_time_us = frame_info->presentation_time;
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estimate_queue_add_value (&frame_clock->dispatch_lateness_us,
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frame_clock->last_dispatch_lateness_us);
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frame_clock->got_measurements_last_frame = FALSE;
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if (frame_info->cpu_time_before_buffer_swap_us != 0 &&
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@ -302,12 +304,12 @@ 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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estimate_queue_add_value (&frame_clock->dispatch_to_swap_us,
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dispatch_to_swap_us);
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estimate_queue_add_value (&frame_clock->swap_to_rendering_done_us,
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swap_to_rendering_done_us);
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estimate_queue_add_value (&frame_clock->swap_to_flip_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->got_measurements_last_frame = TRUE;
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}
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@ -317,6 +319,20 @@ 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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@ -362,12 +378,11 @@ 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 = 0;
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int64_t max_dispatch_to_swap_us = 0;
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int64_t max_swap_to_rendering_done_us = 0;
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int64_t max_swap_to_flip_us = 0;
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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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int i;
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refresh_interval_us = frame_clock->refresh_interval_us;
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@ -376,21 +391,18 @@ 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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for (i = 0; i < ESTIMATE_QUEUE_LENGTH; ++i)
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{
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max_dispatch_lateness_us =
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MAX (max_dispatch_lateness_us,
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frame_clock->dispatch_lateness_us.values[i]);
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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 (max_dispatch_to_swap_us,
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frame_clock->dispatch_to_swap_us.values[i]);
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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 (max_swap_to_rendering_done_us,
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frame_clock->swap_to_rendering_done_us.values[i]);
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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 (max_swap_to_flip_us,
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frame_clock->swap_to_flip_us.values[i]);
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}
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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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@ -706,6 +718,10 @@ 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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frame_clock->last_dispatch_time_us = time_us;
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g_source_set_ready_time (frame_clock->source, -1);
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@ -794,11 +810,10 @@ 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 = 0;
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int64_t max_dispatch_to_swap_us = 0;
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int64_t max_swap_to_rendering_done_us = 0;
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int64_t max_swap_to_flip_us = 0;
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int i;
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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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GString *string;
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string = g_string_new (NULL);
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@ -810,21 +825,18 @@ 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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for (i = 0; i < ESTIMATE_QUEUE_LENGTH; ++i)
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{
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max_dispatch_lateness_us =
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MAX (max_dispatch_lateness_us,
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frame_clock->dispatch_lateness_us.values[i]);
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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 (max_dispatch_to_swap_us,
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frame_clock->dispatch_to_swap_us.values[i]);
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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 (max_swap_to_rendering_done_us,
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frame_clock->swap_to_rendering_done_us.values[i]);
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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 (max_swap_to_flip_us,
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frame_clock->swap_to_flip_us.values[i]);
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}
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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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g_string_append_printf (string, "\nVblank duration: %ld µs +",
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frame_clock->vblank_duration_us);
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