# define LLONG_MAX 9223372036854775807LL
#endif
-#ifndef HISTOGRAM_NUM_BINS
-# define HISTOGRAM_NUM_BINS 1000
-#endif
-
#ifndef HISTOGRAM_DEFAULT_BIN_WIDTH
/* 1048576 = 2^20 ^= 1/1024 s */
# define HISTOGRAM_DEFAULT_BIN_WIDTH 1048576
if (lc->max < latency)
lc->max = latency;
- /* A latency of _exactly_ 1.0 ms should be stored in the buffer 0, so
+ /* A latency of _exactly_ 1.0 ms is stored in the buffer 0, so
* subtract one from the cdtime_t value so that exactly 1.0 ms get sorted
* accordingly. */
bin = (latency - 1) / lc->bin_width;
return (latency_interpolated);
} /* }}} cdtime_t latency_counter_get_percentile */
-cdtime_t latency_counter_get_start_time (const latency_counter_t *lc) /* {{{ */
-{
- if (lc == NULL)
- return (0);
-
- return lc->start_time;
-} /* }}} cdtime_t latency_counter_get_start_time */
-
-double latency_counter_get_rate (const latency_counter_t *lc, /* {{{ */
- const cdtime_t lower, cdtime_t upper, const cdtime_t now)
-{
- cdtime_t lower_bin;
- cdtime_t upper_bin;
- double p;
- double sum = 0;
- size_t i;
-
+double latency_counter_get_rate(const latency_counter_t *lc, /* {{{ */
+ cdtime_t lower, cdtime_t upper,
+ const cdtime_t now) {
if ((lc == NULL) || (lc->num == 0))
- return (0);
-
- if (lower < 1) {
- //sum += lc->zero;
- //lower = 1;
- return (0);
- }
+ return (NAN);
if (upper && (upper < lower))
+ return (NAN);
+ if (lower == upper)
return (0);
- /* A latency of _exactly_ 1.0 ms should be stored in the buffer 0 */
- lower_bin = (lower - 1) / lc->bin_width;
+ /* Buckets have an exclusive lower bound and an inclusive upper bound. That
+ * means that the first bucket, index 0, represents (0-bin_width]. That means
+ * that latency==bin_width needs to result in bin=0, that's why we need to
+ * subtract one before dividing by bin_width. */
+ cdtime_t lower_bin = 0;
+ if (lower)
+ /* lower is *exclusive* => determine bucket for lower+1 */
+ lower_bin = ((lower + 1) - 1) / lc->bin_width;
+ /* lower is greater than the longest latency observed => rate is zero. */
+ if (lower_bin >= HISTOGRAM_NUM_BINS)
+ return (0);
+
+ cdtime_t upper_bin = HISTOGRAM_NUM_BINS - 1;
if (upper)
upper_bin = (upper - 1) / lc->bin_width;
- else
- upper_bin = HISTOGRAM_NUM_BINS - 1;
-
- if (lower_bin >= HISTOGRAM_NUM_BINS)
- lower_bin = HISTOGRAM_NUM_BINS - 1;
if (upper_bin >= HISTOGRAM_NUM_BINS) {
upper_bin = HISTOGRAM_NUM_BINS - 1;
upper = 0;
}
- ERROR("get_rate (%.3f, %.3f): bin_width = %.3f; "
- "lower_bin = %"PRIu64" (%.3f); upper_bin = %"PRIu64" (%.3f);",
- CDTIME_T_TO_DOUBLE (lower),
- CDTIME_T_TO_DOUBLE (upper),
- CDTIME_T_TO_DOUBLE (lc->bin_width),
- lower_bin,
- CDTIME_T_TO_DOUBLE (lc->bin_width * lower_bin),
- upper_bin,
- CDTIME_T_TO_DOUBLE (lc->bin_width * upper_bin)
- );
-
- sum = 0;
- for (i = lower_bin; i <= upper_bin; i++)
- {
- ERROR("SUMM, bin: %d (%.3f), v: %d", i, CDTIME_T_TO_DOUBLE(i * lc->bin_width), lc->histogram[i]);
+ double sum = 0;
+ for (size_t i = lower_bin; i <= upper_bin; i++)
sum += lc->histogram[i];
+
+ if (lower) {
+ /* Approximate ratio of requests in lower_bin, that fall between
+ * lower_bin_boundary and lower. This ratio is then subtracted from sum to
+ * increase accuracy. */
+ cdtime_t lower_bin_boundary = lower_bin * lc->bin_width;
+ assert(lower >= lower_bin_boundary);
+ double lower_ratio =
+ (double)(lower - lower_bin_boundary) / ((double)lc->bin_width);
+ sum -= lower_ratio * lc->histogram[lower_bin];
}
- ERROR("sum before interpolations: %.3f", sum);
-
- //v1//p = ((double)lower - (double)(lower_bin + 1) * (double)lc->bin_width) / (double)lc->bin_width;
- p = ((double)lower - (double)(lower_bin + 0) * (double)lc->bin_width - (double)DOUBLE_TO_CDTIME_T(0.001)) / (double)lc->bin_width;
- ERROR("interpolation 1: p=%lf, 1=%"PRIu64" (%.3f), 2=%"PRIu64" (%.3f), 3=%"PRIu64" (%.3f); lower_bin: %"PRIu64"",
- p,
- //1
- lower - DOUBLE_TO_CDTIME_T(0.001),
- CDTIME_T_TO_DOUBLE (lower - (double)DOUBLE_TO_CDTIME_T(0.001)),
- //2
- (lower_bin + 0) * lc->bin_width,
- CDTIME_T_TO_DOUBLE ((lower_bin + 0) * lc->bin_width),
- //3
- lc->bin_width,
- CDTIME_T_TO_DOUBLE (lc->bin_width),
- lower_bin
- );
- sum -= p * lc->histogram[lower_bin];
-/*
- if (upper && upper_bin == lower_bin) {
- //p = ((double)(upper_bin + 1) * (double)lc->bin_width - (double)upper) / (double)lc->bin_width;
- p = (double)(upper_bin + 1) - (double)upper / (double)lc->bin_width;
- ERROR("interpolation 2: p=%lf, 1=%"PRIu64" (%.3f), 2=%"PRIu64" (%.3f), 3=%.3f (%.3f); upper_bin: %"PRIu64"",
- p,
- //1
- (upper_bin + 1) * lc->bin_width,
- CDTIME_T_TO_DOUBLE ((upper_bin + 1) * lc->bin_width),
- //2
- upper,
- CDTIME_T_TO_DOUBLE (upper),
- //3
- (double)lc->bin_width,
- CDTIME_T_TO_DOUBLE (lc->bin_width),
- upper_bin
- );
- sum -= p * lc->histogram[upper_bin];
- }
- else
- */
- if (upper && upper < (upper_bin + 1) * lc->bin_width)
- {
- // p = ((upper_bin + 1) * bin_width - upper ) / bin_width;
-
- //p = ((double)upper - (double)(upper_bin + 0) * (double)lc->bin_width) / (double)lc->bin_width;
- p = ((double)(upper_bin + 1) * (double)lc->bin_width - (double)upper) / (double)lc->bin_width;
- ERROR("interpolation 3: p=%lf, 1=%"PRIu64" (%.3f), 2=%"PRIu64" (%.3f), 3=%"PRIu64" (%.3f); upper_bin: %"PRIu64"",
- p,
- //1
- (upper_bin + 1) * lc->bin_width,
- CDTIME_T_TO_DOUBLE ((upper_bin + 1) * lc->bin_width),
- //2
- upper,
- CDTIME_T_TO_DOUBLE (upper),
- //3
- lc->bin_width,
- CDTIME_T_TO_DOUBLE (lc->bin_width),
- upper_bin
- );
- sum -= p * lc->histogram[upper_bin];
+
+ if (upper) {
+ /* As above: approximate ratio of requests in upper_bin, that fall between
+ * upper and upper_bin_boundary. */
+ cdtime_t upper_bin_boundary = (upper_bin + 1) * lc->bin_width;
+ assert(upper <= upper_bin_boundary);
+ double ratio = (double)(upper_bin_boundary - upper) / (double)lc->bin_width;
+ sum -= ratio * lc->histogram[upper_bin];
}
- return sum / (CDTIME_T_TO_DOUBLE (now - lc->start_time));
+ return sum / (CDTIME_T_TO_DOUBLE(now - lc->start_time));
} /* }}} double latency_counter_get_rate */
-
/* vim: set sw=2 sts=2 et fdm=marker : */
projects / collectd.git / blobdiff