Commit 5e1974fc authored by Sebastian Dröge's avatar Sebastian Dröge 🍵
Browse files

ptp: Add #defines to enable/disable improvements for unreliable networks

We should do some more measurements with all these and check how much sense
they make for PTP. Also enabling them means not following IEEE1588-2008 by the
letter anymore.

https://bugzilla.gnome.org/show_bug.cgi?id=749391
parent 8d777598
......@@ -73,6 +73,33 @@ GST_DEBUG_CATEGORY_STATIC (ptp_debug);
/* IEEE 1588 7.7.3.1 */
#define PTP_ANNOUNCE_RECEIPT_TIMEOUT 4
/* Use a running average for calculating the mean path delay instead
* of just using the last measurement. Enabling this helps in unreliable
* networks, like wifi, with often changing delays
*
* Undef for following IEEE1588-2008 by the letter
*/
#define USE_RUNNING_AVERAGE_DELAY 1
/* Filter out any measurements that are above a certain threshold compared to
* previous measurements. Enabling this helps filtering out outliers that
* happen fairly often in unreliable networks, like wifi.
*
* Undef for following IEEE1588-2008 by the letter
*/
#define USE_MEASUREMENT_FILTERING 1
/* Select the first clock from which we capture a SYNC message as the master
* clock of the domain until we are ready to run the best master clock
* algorithm. This allows faster syncing but might mean a change of the master
* clock in the beginning. As all clocks in a domain are supposed to use the
* same time, this shouldn't be much of a problem.
*
* Undef for following IEEE1588-2008 by the letter
*/
#define USE_OPPORTUNISTIC_CLOCK_SELECTION 1
/* How many updates should be skipped at maximum when using USE_MEASUREMENT_FILTERING */
#define MAX_SKIPPED_UPDATES 5
typedef enum
......@@ -988,14 +1015,18 @@ static void
update_ptp_time (PtpDomainData * domain, PtpPendingSync * sync)
{
GstClockTime internal_time, external_time, rate_num, rate_den;
GstClockTime corrected_ptp_time, corrected_local_time;
gdouble r_squared = 0.0;
gboolean synced;
GstClockTimeDiff discont = 0;
GstClockTime estimated_ptp_time = GST_CLOCK_TIME_NONE;
#ifdef USE_MEASUREMENT_FILTERING
GstClockTime orig_internal_time, orig_external_time, orig_rate_num,
orig_rate_den;
GstClockTime corrected_ptp_time, corrected_local_time;
GstClockTime new_estimated_ptp_time;
GstClockTime max_discont, estimated_ptp_time_min, estimated_ptp_time_max;
gdouble r_squared;
gboolean synced, now_synced;
GstClockTimeDiff discont = 0;
GstClockTime estimated_ptp_time = GST_CLOCK_TIME_NONE, new_estimated_ptp_time;
gboolean now_synced;
/* We check this here and when updating the mean path delay, because
* we can get here without a delay response too */
......@@ -1008,6 +1039,7 @@ update_ptp_time (PtpDomainData * domain, PtpPendingSync * sync)
GST_TIME_ARGS (domain->mean_path_delay));
goto out;
}
#endif
/* IEEE 1588 11.2 */
corrected_ptp_time =
......@@ -1020,6 +1052,7 @@ update_ptp_time (PtpDomainData * domain, PtpPendingSync * sync)
gst_clock_set_calibration (domain->domain_clock, corrected_local_time,
corrected_ptp_time, 1, 1);
#ifdef USE_MEASUREMENT_FILTERING
/* Check if the corrected PTP time is +/- 3/4 RTT around what we would
* estimate with our present knowledge about the clock
*/
......@@ -1135,8 +1168,34 @@ update_ptp_time (PtpDomainData * domain, PtpPendingSync * sync)
domain->last_local_time = corrected_local_time;
}
out:
#else
GST_DEBUG ("Adding observation for domain %u: %" GST_TIME_FORMAT " - %"
GST_TIME_FORMAT, domain->domain,
GST_TIME_ARGS (corrected_ptp_time), GST_TIME_ARGS (corrected_local_time));
gst_clock_get_calibration (GST_CLOCK_CAST (domain->domain_clock),
&internal_time, &external_time, &rate_num, &rate_den);
estimated_ptp_time = corrected_local_time;
estimated_ptp_time =
gst_clock_adjust_with_calibration (GST_CLOCK_CAST
(domain->domain_clock), estimated_ptp_time, internal_time,
external_time, rate_num, rate_den);
gst_clock_add_observation (domain->domain_clock,
corrected_local_time, corrected_ptp_time, &r_squared);
gst_clock_get_calibration (GST_CLOCK_CAST (domain->domain_clock),
&internal_time, &external_time, &rate_num, &rate_den);
synced = TRUE;
domain->last_ptp_time = corrected_ptp_time;
domain->last_local_time = corrected_local_time;
#endif
#ifdef USE_MEASUREMENT_FILTERING
out:
#endif
if (g_atomic_int_get (&domain_stats_n_hooks)) {
GstStructure *stats = gst_structure_new (GST_PTP_STATISTICS_TIME_UPDATED,
"domain", G_TYPE_UINT, domain->domain,
......@@ -1172,6 +1231,7 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
(sync->correction_field_sync + sync->correction_field_delay +
32768) / 65536) / 2;
#ifdef USE_RUNNING_AVERAGE_DELAY
/* Track an average round trip time, for a bit of smoothing */
/* Always update before discarding a sample, so genuine changes in
* the network get picked up, eventually */
......@@ -1183,7 +1243,11 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
else
domain->mean_path_delay =
(15 * domain->mean_path_delay + mean_path_delay) / 16;
#else
domain->mean_path_delay = mean_path_delay;
#endif
#ifdef USE_MEASUREMENT_FILTERING
if (sync->follow_up_recv_time_local != GST_CLOCK_TIME_NONE &&
domain->mean_path_delay != 0
&& sync->follow_up_recv_time_local >
......@@ -1204,9 +1268,12 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
ret = FALSE;
goto out;
}
#endif
delay_req_delay =
sync->delay_resp_recv_time_local - sync->delay_req_send_time_local;
#ifdef USE_MEASUREMENT_FILTERING
/* delay_req_delay is a RTT, so 2 times the path delay */
if (delay_req_delay > 4 * domain->mean_path_delay) {
GST_WARNING ("Delay-request-response delay for domain %u too big: %"
......@@ -1216,6 +1283,7 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
ret = FALSE;
goto out;
}
#endif
ret = TRUE;
......@@ -1225,7 +1293,9 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
GST_DEBUG ("Delay request delay for domain %u: %" GST_TIME_FORMAT,
domain->domain, GST_TIME_ARGS (delay_req_delay));
#ifdef USE_MEASUREMENT_FILTERING
out:
#endif
if (g_atomic_int_get (&domain_stats_n_hooks)) {
GstStructure *stats =
gst_structure_new (GST_PTP_STATISTICS_PATH_DELAY_MEASURED,
......@@ -1282,10 +1352,15 @@ handle_sync_message (PtpMessage * msg, GstClockTime receive_time)
&msg->source_port_identity) != 0)
return;
#ifdef USE_OPPORTUNISTIC_CLOCK_SELECTION
/* Opportunistic selection of master clock */
if (!domain->have_master_clock)
memcpy (&domain->master_clock_identity, &msg->source_port_identity,
sizeof (PtpClockIdentity));
#else
if (!domain->have_master_clock)
return;
#endif
domain->sync_interval = log2_to_clock_time (msg->log_message_interval);
......
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