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frame-clock: Simplify dynamic max render time calculation

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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 2022-07-04 18:57:45 +02:00 committed by Marge Bot
parent 99850f4645
commit ca341ef1ea
1 changed files with 88 additions and 76 deletions
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164
clutter/clutter/clutter-frame-clock.c
View File

@ -34,17 +34,6 @@ enum
static guint signals[N_SIGNALS]; static guint signals[N_SIGNALS];
/* An estimate queue holds several int64_t values. Adding a new value to the
* queue overwrites the oldest value.
*/
#define ESTIMATE_QUEUE_LENGTH 16
typedef struct _EstimateQueue
{
int64_t values[ESTIMATE_QUEUE_LENGTH];
int next_index;
} EstimateQueue;
#define SYNC_DELAY_FALLBACK_FRACTION 0.875 #define SYNC_DELAY_FALLBACK_FRACTION 0.875
typedef struct _ClutterFrameListener typedef struct _ClutterFrameListener
@ -97,14 +86,21 @@ struct _ClutterFrameClock
/* Last KMS buffer submission time. */ /* Last KMS buffer submission time. */
int64_t last_flip_time_us; int64_t last_flip_time_us;
/* Last few durations between desired and effective dispatch start. */ /* Last time we promoted short term durations to long term ones */
EstimateQueue dispatch_lateness_us; int64_t longterm_promotion_us;
/* Last few durations between dispatch start and buffer swap. */
EstimateQueue dispatch_to_swap_us; /* Short & long term maximum values */
/* Last few durations between buffer swap and GPU rendering finish. */ struct {
EstimateQueue swap_to_rendering_done_us; /* Duration between desired and effective dispatch start. */
/* Last few durations between buffer swap and KMS submission. */ int64_t max_dispatch_lateness_us;
EstimateQueue swap_to_flip_us; /* Duration between dispatch start and buffer swap. */
int64_t max_dispatch_to_swap_us;
/* Duration between buffer swap and GPU rendering finish. */
int64_t max_swap_to_rendering_done_us;
/* Duration between buffer swap and KMS submission. */
int64_t max_swap_to_flip_us;
} shortterm, longterm;
/* If we got new measurements last frame. */ /* If we got new measurements last frame. */
gboolean got_measurements_last_frame; gboolean got_measurements_last_frame;
@ -119,14 +115,6 @@ struct _ClutterFrameClock
G_DEFINE_TYPE (ClutterFrameClock, clutter_frame_clock, G_DEFINE_TYPE (ClutterFrameClock, clutter_frame_clock,
G_TYPE_OBJECT) G_TYPE_OBJECT)
static void
estimate_queue_add_value (EstimateQueue *queue,
int64_t value)
{
queue->values[queue->next_index] = value;
queue->next_index = (queue->next_index + 1) % ESTIMATE_QUEUE_LENGTH;
}
float float
clutter_frame_clock_get_refresh_rate (ClutterFrameClock *frame_clock) clutter_frame_clock_get_refresh_rate (ClutterFrameClock *frame_clock)
{ {
@ -227,6 +215,23 @@ maybe_reschedule_update (ClutterFrameClock *frame_clock)
} }
} }
static void
update_longterm_max (int64_t *longterm_max,
int64_t *shortterm_max)
{
/* Do not update long term max if there has been no measurement in over a second. */
if (!*shortterm_max)
return;
if (*longterm_max > *shortterm_max)
/* Exponential drop-off toward the short term max */
*longterm_max -= (*longterm_max - *shortterm_max) / 2;
else
*longterm_max = *shortterm_max;
*shortterm_max = 0;
}
void void
clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock, clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
ClutterFrameInfo *frame_info) ClutterFrameInfo *frame_info)
@ -276,9 +281,6 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
if (frame_info->presentation_time > 0) if (frame_info->presentation_time > 0)
frame_clock->last_presentation_time_us = frame_info->presentation_time; frame_clock->last_presentation_time_us = frame_info->presentation_time;
estimate_queue_add_value (&frame_clock->dispatch_lateness_us,
frame_clock->last_dispatch_lateness_us);
frame_clock->got_measurements_last_frame = FALSE; frame_clock->got_measurements_last_frame = FALSE;
if (frame_info->cpu_time_before_buffer_swap_us != 0 && if (frame_info->cpu_time_before_buffer_swap_us != 0 &&
@ -302,12 +304,12 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
swap_to_rendering_done_us, swap_to_rendering_done_us,
swap_to_flip_us); swap_to_flip_us);
estimate_queue_add_value (&frame_clock->dispatch_to_swap_us, frame_clock->shortterm.max_dispatch_to_swap_us =
dispatch_to_swap_us); MAX (frame_clock->shortterm.max_dispatch_to_swap_us, dispatch_to_swap_us);
estimate_queue_add_value (&frame_clock->swap_to_rendering_done_us, frame_clock->shortterm.max_swap_to_rendering_done_us =
swap_to_rendering_done_us); MAX (frame_clock->shortterm.max_swap_to_rendering_done_us, swap_to_rendering_done_us);
estimate_queue_add_value (&frame_clock->swap_to_flip_us, frame_clock->shortterm.max_swap_to_flip_us =
swap_to_flip_us); MAX (frame_clock->shortterm.max_swap_to_flip_us, swap_to_flip_us);
frame_clock->got_measurements_last_frame = TRUE; frame_clock->got_measurements_last_frame = TRUE;
} }
@ -317,6 +319,20 @@ clutter_frame_clock_notify_presented (ClutterFrameClock *frame_clock,
frame_clock->last_dispatch_lateness_us); frame_clock->last_dispatch_lateness_us);
} }
if (frame_info->presentation_time - frame_clock->longterm_promotion_us > G_USEC_PER_SEC)
{
update_longterm_max (&frame_clock->longterm.max_dispatch_lateness_us,
&frame_clock->shortterm.max_dispatch_lateness_us);
update_longterm_max (&frame_clock->longterm.max_dispatch_to_swap_us,
&frame_clock->shortterm.max_dispatch_to_swap_us);
update_longterm_max (&frame_clock->longterm.max_swap_to_rendering_done_us,
&frame_clock->shortterm.max_swap_to_rendering_done_us);
update_longterm_max (&frame_clock->longterm.max_swap_to_flip_us,
&frame_clock->shortterm.max_swap_to_flip_us);
frame_clock->longterm_promotion_us = frame_info->presentation_time;
}
if (frame_info->refresh_rate > 1.0) if (frame_info->refresh_rate > 1.0)
{ {
clutter_frame_clock_set_refresh_rate (frame_clock, clutter_frame_clock_set_refresh_rate (frame_clock,
@ -362,12 +378,11 @@ static int64_t
clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock) clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock)
{ {
int64_t refresh_interval_us; int64_t refresh_interval_us;
int64_t max_dispatch_lateness_us = 0; int64_t max_dispatch_lateness_us;
int64_t max_dispatch_to_swap_us = 0; int64_t max_dispatch_to_swap_us;
int64_t max_swap_to_rendering_done_us = 0; int64_t max_swap_to_rendering_done_us;
int64_t max_swap_to_flip_us = 0; int64_t max_swap_to_flip_us;
int64_t max_render_time_us; int64_t max_render_time_us;
int i;
refresh_interval_us = frame_clock->refresh_interval_us; refresh_interval_us = frame_clock->refresh_interval_us;
@ -376,21 +391,18 @@ clutter_frame_clock_compute_max_render_time_us (ClutterFrameClock *frame_clock)
CLUTTER_DEBUG_DISABLE_DYNAMIC_MAX_RENDER_TIME)) CLUTTER_DEBUG_DISABLE_DYNAMIC_MAX_RENDER_TIME))
return refresh_interval_us * SYNC_DELAY_FALLBACK_FRACTION; return refresh_interval_us * SYNC_DELAY_FALLBACK_FRACTION;
for (i = 0; i < ESTIMATE_QUEUE_LENGTH; ++i) max_dispatch_lateness_us =
{ MAX (frame_clock->longterm.max_dispatch_lateness_us,
max_dispatch_lateness_us = frame_clock->shortterm.max_dispatch_lateness_us);
MAX (max_dispatch_lateness_us, max_dispatch_to_swap_us =
frame_clock->dispatch_lateness_us.values[i]); MAX (frame_clock->longterm.max_dispatch_to_swap_us,
max_dispatch_to_swap_us = frame_clock->shortterm.max_dispatch_to_swap_us);
MAX (max_dispatch_to_swap_us, max_swap_to_rendering_done_us =
frame_clock->dispatch_to_swap_us.values[i]); MAX (frame_clock->longterm.max_swap_to_rendering_done_us,
max_swap_to_rendering_done_us = frame_clock->shortterm.max_swap_to_rendering_done_us);
MAX (max_swap_to_rendering_done_us, max_swap_to_flip_us =
frame_clock->swap_to_rendering_done_us.values[i]); MAX (frame_clock->longterm.max_swap_to_flip_us,
max_swap_to_flip_us = frame_clock->shortterm.max_swap_to_flip_us);
MAX (max_swap_to_flip_us,
frame_clock->swap_to_flip_us.values[i]);
}
/* Max render time shows how early the frame clock needs to be dispatched /* Max render time shows how early the frame clock needs to be dispatched
* to make it to the predicted next presentation time. It is composed of: * to make it to the predicted next presentation time. It is composed of:
@ -706,6 +718,10 @@ clutter_frame_clock_dispatch (ClutterFrameClock *frame_clock,
else else
frame_clock->last_dispatch_lateness_us = lateness_us; frame_clock->last_dispatch_lateness_us = lateness_us;
frame_clock->shortterm.max_dispatch_lateness_us =
MAX (frame_clock->shortterm.max_dispatch_lateness_us,
frame_clock->last_dispatch_lateness_us);
frame_clock->last_dispatch_time_us = time_us; frame_clock->last_dispatch_time_us = time_us;
g_source_set_ready_time (frame_clock->source, -1); g_source_set_ready_time (frame_clock->source, -1);
@ -794,11 +810,10 @@ clutter_frame_clock_record_flip_time (ClutterFrameClock *frame_clock,
GString * GString *
clutter_frame_clock_get_max_render_time_debug_info (ClutterFrameClock *frame_clock) clutter_frame_clock_get_max_render_time_debug_info (ClutterFrameClock *frame_clock)
{ {
int64_t max_dispatch_lateness_us = 0; int64_t max_dispatch_lateness_us;
int64_t max_dispatch_to_swap_us = 0; int64_t max_dispatch_to_swap_us;
int64_t max_swap_to_rendering_done_us = 0; int64_t max_swap_to_rendering_done_us;
int64_t max_swap_to_flip_us = 0; int64_t max_swap_to_flip_us;
int i;
GString *string; GString *string;
string = g_string_new (NULL); string = g_string_new (NULL);
@ -810,21 +825,18 @@ clutter_frame_clock_get_max_render_time_debug_info (ClutterFrameClock *frame_clo
else else
g_string_append_printf (string, " (no measurements last frame)"); g_string_append_printf (string, " (no measurements last frame)");
for (i = 0; i < ESTIMATE_QUEUE_LENGTH; ++i) max_dispatch_lateness_us =
{ MAX (frame_clock->longterm.max_dispatch_lateness_us,
max_dispatch_lateness_us = frame_clock->shortterm.max_dispatch_lateness_us);
MAX (max_dispatch_lateness_us, max_dispatch_to_swap_us =
frame_clock->dispatch_lateness_us.values[i]); MAX (frame_clock->longterm.max_dispatch_to_swap_us,
max_dispatch_to_swap_us = frame_clock->shortterm.max_dispatch_to_swap_us);
MAX (max_dispatch_to_swap_us, max_swap_to_rendering_done_us =
frame_clock->dispatch_to_swap_us.values[i]); MAX (frame_clock->longterm.max_swap_to_rendering_done_us,
max_swap_to_rendering_done_us = frame_clock->shortterm.max_swap_to_rendering_done_us);
MAX (max_swap_to_rendering_done_us, max_swap_to_flip_us =
frame_clock->swap_to_rendering_done_us.values[i]); MAX (frame_clock->longterm.max_swap_to_flip_us,
max_swap_to_flip_us = frame_clock->shortterm.max_swap_to_flip_us);
MAX (max_swap_to_flip_us,
frame_clock->swap_to_flip_us.values[i]);
}
g_string_append_printf (string, "\nVblank duration: %ld µs +", g_string_append_printf (string, "\nVblank duration: %ld µs +",
frame_clock->vblank_duration_us); frame_clock->vblank_duration_us);