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Resurrect source combining

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This is based on the code that was removed in CVS revision 1.3 of
sources.c. The weighting is simplified and the code is moved to a new
function.
This commit is contained in:
Miroslav Lichvar 2011-06-29 18:45:31 +02:00
parent 8aa9eb19c8
commit 18a66a2ba8
1 changed files with 57 additions and 2 deletions
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59
sources.c
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@ -410,6 +410,56 @@ source_to_string(SRC_Instance inst)
return NULL;
}
/* ================================================== */
static void
combine_sources(int n_sel_sources, struct timeval *ref_time, double *offset,
double *offset_sd, double *frequency, double *skew)
{
struct timeval src_ref_time;
double src_offset, src_offset_sd, src_frequency, src_skew;
double src_root_delay, src_root_dispersion, elapsed;
double weight, sum_weight, sum_offset, sum2_offset_sd, sum_frequency, sum_skew;
int i, index;
sum_weight = sum_offset = sum2_offset_sd = sum_frequency = sum_skew = 0.0;
for (i = 0; i < n_sel_sources; i++) {
index = sel_sources[i];
SST_GetTrackingData(sources[index]->stats, &src_ref_time,
&src_offset, &src_offset_sd,
&src_frequency, &src_skew,
&src_root_delay, &src_root_dispersion);
UTI_DiffTimevalsToDouble(&elapsed, ref_time, &src_ref_time);
src_offset += elapsed * src_frequency;
weight = 1.0 / sources[index]->sel_info.root_distance;
#ifdef TRACEON
LOG(LOGS_INFO, LOGF_Sources, "combining index=%d weight=%e offset=%e sd=%e freq=%e skew=%e",
index, weight, src_offset, src_offset_sd, src_frequency, src_skew);
#endif
sum_weight += weight;
sum_offset += weight * src_offset;
sum2_offset_sd += weight * (src_offset_sd * src_offset_sd +
(src_offset - *offset) * (src_offset - *offset));
sum_frequency += weight * src_frequency;
sum_skew += weight * src_skew;
}
assert(sum_weight > 0.0);
*offset = sum_offset / sum_weight;
*offset_sd = sqrt(sum2_offset_sd / sum_weight);
*frequency = sum_frequency / sum_weight;
*skew = sum_skew / sum_weight;
#ifdef TRACEON
LOG(LOGS_INFO, LOGF_Sources, "combined result offset=%e sd=%e freq=%e skew=%e",
*offset, *offset_sd, *frequency, *skew);
#endif
}
/* ================================================== */
/* This function selects the current reference from amongst the pool
of sources we are holding.
@ -840,14 +890,19 @@ SRC_SelectSource(uint32_t match_refid)
if (selected_source_index != old_selected_index ||
match_refid == sources[selected_source_index]->ref_id) {
/* Now just use the statistics of the selected source for
trimming the local clock */
/* Now just use the statistics of the selected source combined with
the other selectable sources for trimming the local clock */
SST_GetTrackingData(sources[selected_source_index]->stats, &ref_time,
&src_offset, &src_offset_sd,
&src_frequency, &src_skew,
&src_root_delay, &src_root_dispersion);
if (n_sel_sources > 1) {
combine_sources(n_sel_sources, &ref_time, &src_offset,
&src_offset_sd, &src_frequency, &src_skew);
}
REF_SetReference(sources[selected_source_index]->sel_info.stratum,
leap_status,
sources[selected_source_index]->ref_id,