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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
This commit is contained in:
Sebastian Dröge
parent
8d77759834
commit
5e1974fc08
1 changed files with 81 additions and 6 deletions
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@ -73,6 +73,33 @@ GST_DEBUG_CATEGORY_STATIC (ptp_debug);
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/* IEEE 1588 7.7.3.1 */
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#define PTP_ANNOUNCE_RECEIPT_TIMEOUT 4
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/* Use a running average for calculating the mean path delay instead
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* of just using the last measurement. Enabling this helps in unreliable
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* networks, like wifi, with often changing delays
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*
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* Undef for following IEEE1588-2008 by the letter
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*/
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#define USE_RUNNING_AVERAGE_DELAY 1
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/* Filter out any measurements that are above a certain threshold compared to
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* previous measurements. Enabling this helps filtering out outliers that
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* happen fairly often in unreliable networks, like wifi.
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*
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* Undef for following IEEE1588-2008 by the letter
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*/
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#define USE_MEASUREMENT_FILTERING 1
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/* Select the first clock from which we capture a SYNC message as the master
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* clock of the domain until we are ready to run the best master clock
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* algorithm. This allows faster syncing but might mean a change of the master
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* clock in the beginning. As all clocks in a domain are supposed to use the
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* same time, this shouldn't be much of a problem.
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*
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* Undef for following IEEE1588-2008 by the letter
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*/
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#define USE_OPPORTUNISTIC_CLOCK_SELECTION 1
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/* How many updates should be skipped at maximum when using USE_MEASUREMENT_FILTERING */
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#define MAX_SKIPPED_UPDATES 5
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typedef enum
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@ -988,14 +1015,18 @@ static void
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update_ptp_time (PtpDomainData * domain, PtpPendingSync * sync)
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{
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GstClockTime internal_time, external_time, rate_num, rate_den;
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GstClockTime corrected_ptp_time, corrected_local_time;
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gdouble r_squared = 0.0;
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gboolean synced;
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GstClockTimeDiff discont = 0;
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GstClockTime estimated_ptp_time = GST_CLOCK_TIME_NONE;
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#ifdef USE_MEASUREMENT_FILTERING
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GstClockTime orig_internal_time, orig_external_time, orig_rate_num,
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orig_rate_den;
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GstClockTime corrected_ptp_time, corrected_local_time;
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GstClockTime new_estimated_ptp_time;
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GstClockTime max_discont, estimated_ptp_time_min, estimated_ptp_time_max;
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gdouble r_squared;
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gboolean synced, now_synced;
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GstClockTimeDiff discont = 0;
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GstClockTime estimated_ptp_time = GST_CLOCK_TIME_NONE, new_estimated_ptp_time;
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gboolean now_synced;
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/* We check this here and when updating the mean path delay, because
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* we can get here without a delay response too */
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@ -1008,6 +1039,7 @@ update_ptp_time (PtpDomainData * domain, PtpPendingSync * sync)
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GST_TIME_ARGS (domain->mean_path_delay));
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goto out;
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}
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#endif
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/* IEEE 1588 11.2 */
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corrected_ptp_time =
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@ -1020,6 +1052,7 @@ update_ptp_time (PtpDomainData * domain, PtpPendingSync * sync)
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gst_clock_set_calibration (domain->domain_clock, corrected_local_time,
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corrected_ptp_time, 1, 1);
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#ifdef USE_MEASUREMENT_FILTERING
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/* Check if the corrected PTP time is +/- 3/4 RTT around what we would
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* estimate with our present knowledge about the clock
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*/
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@ -1135,8 +1168,34 @@ update_ptp_time (PtpDomainData * domain, PtpPendingSync * sync)
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domain->last_local_time = corrected_local_time;
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}
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out:
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#else
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GST_DEBUG ("Adding observation for domain %u: %" GST_TIME_FORMAT " - %"
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GST_TIME_FORMAT, domain->domain,
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GST_TIME_ARGS (corrected_ptp_time), GST_TIME_ARGS (corrected_local_time));
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gst_clock_get_calibration (GST_CLOCK_CAST (domain->domain_clock),
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&internal_time, &external_time, &rate_num, &rate_den);
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estimated_ptp_time = corrected_local_time;
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estimated_ptp_time =
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gst_clock_adjust_with_calibration (GST_CLOCK_CAST
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(domain->domain_clock), estimated_ptp_time, internal_time,
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external_time, rate_num, rate_den);
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gst_clock_add_observation (domain->domain_clock,
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corrected_local_time, corrected_ptp_time, &r_squared);
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gst_clock_get_calibration (GST_CLOCK_CAST (domain->domain_clock),
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&internal_time, &external_time, &rate_num, &rate_den);
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synced = TRUE;
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domain->last_ptp_time = corrected_ptp_time;
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domain->last_local_time = corrected_local_time;
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#endif
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#ifdef USE_MEASUREMENT_FILTERING
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out:
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#endif
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if (g_atomic_int_get (&domain_stats_n_hooks)) {
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GstStructure *stats = gst_structure_new (GST_PTP_STATISTICS_TIME_UPDATED,
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"domain", G_TYPE_UINT, domain->domain,
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@ -1172,6 +1231,7 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
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(sync->correction_field_sync + sync->correction_field_delay +
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32768) / 65536) / 2;
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#ifdef USE_RUNNING_AVERAGE_DELAY
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/* Track an average round trip time, for a bit of smoothing */
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/* Always update before discarding a sample, so genuine changes in
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* the network get picked up, eventually */
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@ -1183,7 +1243,11 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
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else
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domain->mean_path_delay =
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(15 * domain->mean_path_delay + mean_path_delay) / 16;
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#else
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domain->mean_path_delay = mean_path_delay;
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#endif
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#ifdef USE_MEASUREMENT_FILTERING
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if (sync->follow_up_recv_time_local != GST_CLOCK_TIME_NONE &&
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domain->mean_path_delay != 0
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&& sync->follow_up_recv_time_local >
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@ -1204,9 +1268,12 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
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ret = FALSE;
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goto out;
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}
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#endif
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delay_req_delay =
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sync->delay_resp_recv_time_local - sync->delay_req_send_time_local;
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#ifdef USE_MEASUREMENT_FILTERING
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/* delay_req_delay is a RTT, so 2 times the path delay */
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if (delay_req_delay > 4 * domain->mean_path_delay) {
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GST_WARNING ("Delay-request-response delay for domain %u too big: %"
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@ -1216,6 +1283,7 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
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ret = FALSE;
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goto out;
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}
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#endif
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ret = TRUE;
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@ -1225,7 +1293,9 @@ update_mean_path_delay (PtpDomainData * domain, PtpPendingSync * sync)
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GST_DEBUG ("Delay request delay for domain %u: %" GST_TIME_FORMAT,
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domain->domain, GST_TIME_ARGS (delay_req_delay));
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#ifdef USE_MEASUREMENT_FILTERING
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out:
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#endif
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if (g_atomic_int_get (&domain_stats_n_hooks)) {
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GstStructure *stats =
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gst_structure_new (GST_PTP_STATISTICS_PATH_DELAY_MEASURED,
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@ -1282,10 +1352,15 @@ handle_sync_message (PtpMessage * msg, GstClockTime receive_time)
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&msg->source_port_identity) != 0)
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return;
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#ifdef USE_OPPORTUNISTIC_CLOCK_SELECTION
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/* Opportunistic selection of master clock */
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if (!domain->have_master_clock)
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memcpy (&domain->master_clock_identity, &msg->source_port_identity,
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sizeof (PtpClockIdentity));
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#else
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if (!domain->have_master_clock)
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return;
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#endif
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domain->sync_interval = log2_to_clock_time (msg->log_message_interval);
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