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sourcestats: update offset estimate when regression fails

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If there are too few samples to make a regression, at least update the
offset estimate from the last sample and keep the previous frequency
offset unchanged. Also, reset the error estimates.
This commit is contained in:
Miroslav Lichvar 2019-08-05 15:25:04 +02:00
parent 5e8ed72b89
commit 24134c78e8
1 changed files with 17 additions and 3 deletions
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20
sourcestats.c
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@ -54,6 +54,9 @@
/* The minimum standard deviation */
#define MIN_STDDEV 1.0e-9
/* The worst case bound on an unknown standard deviation of the offset */
#define WORST_CASE_STDDEV_BOUND 4.0
/* The asymmetry of network jitter when all jitter is in one direction */
#define MAX_ASYMMETRY 0.5
@ -249,9 +252,9 @@ SST_ResetInstance(SST_Stats inst)
inst->estimated_frequency_sd = WORST_CASE_FREQ_BOUND;
inst->skew = WORST_CASE_FREQ_BOUND;
inst->estimated_offset = 0.0;
inst->estimated_offset_sd = 86400.0; /* Assume it's at least within a day! */
inst->estimated_offset_sd = WORST_CASE_STDDEV_BOUND;
UTI_ZeroTimespec(&inst->offset_time);
inst->std_dev = 4.0;
inst->std_dev = WORST_CASE_STDDEV_BOUND;
inst->nruns = 0;
inst->asymmetry_run = 0;
inst->asymmetry = 0.0;
@ -603,9 +606,20 @@ SST_DoNewRegression(SST_Stats inst)
times_back_start = inst->runs_samples + best_start;
prune_register(inst, best_start);
} else {
inst->estimated_frequency = 0.0;
inst->estimated_frequency_sd = WORST_CASE_FREQ_BOUND;
inst->skew = WORST_CASE_FREQ_BOUND;
inst->estimated_offset_sd = WORST_CASE_STDDEV_BOUND;
inst->std_dev = WORST_CASE_STDDEV_BOUND;
inst->nruns = 0;
if (inst->n_samples > 0) {
inst->estimated_offset = inst->offsets[inst->last_sample];
inst->offset_time = inst->sample_times[inst->last_sample];
} else {
inst->estimated_offset = 0.0;
UTI_ZeroTimespec(&inst->offset_time);
}
times_back_start = 0;
}