From: Pavel Rochnyack Date: Sun, 20 Mar 2016 09:43:36 +0000 (+0600) Subject: statsd, utils_latency: allow to reduce bin width X-Git-Tag: collectd-5.6.0~58 X-Git-Url: https://git.tokkee.org/?a=commitdiff_plain;h=8737bfd2e356a35bbef30ed2185c566cd61bca0b;p=collectd.git statsd, utils_latency: allow to reduce bin width --- diff --git a/src/utils_latency.c b/src/utils_latency.c index bfb9292c..c67752a3 100644 --- a/src/utils_latency.c +++ b/src/utils_latency.c @@ -125,8 +125,8 @@ latency_counter_t *latency_counter_create (void) /* {{{ */ if (lc == NULL) return (NULL); - latency_counter_reset (lc); lc->bin_width = HISTOGRAM_DEFAULT_BIN_WIDTH; + latency_counter_reset (lc); return (lc); } /* }}} latency_counter_t *latency_counter_create */ @@ -175,6 +175,28 @@ void latency_counter_reset (latency_counter_t *lc) /* {{{ */ return; cdtime_t bin_width = lc->bin_width; + cdtime_t max_bin = (lc->max - 1) / lc->bin_width; + +/* + If max latency is REDUCE_THRESHOLD times less than histogram's range, + then cut it in half. REDUCE_THRESHOLD must be >= 2. + Value of 4 is selected to reduce frequent changes of bin width. +*/ +#define REDUCE_THRESHOLD 4 + if ((lc->num > 0) && (lc->bin_width >= HISTOGRAM_DEFAULT_BIN_WIDTH * 2) + && (max_bin < HISTOGRAM_NUM_BINS / REDUCE_THRESHOLD)) + { + /* new bin width will be the previous power of 2 */ + bin_width = bin_width / 2; + + DEBUG("utils_latency: latency_counter_reset: max_latency = %.3f; " + "max_bin = %"PRIu64"; old_bin_width = %.3f; new_bin_width = %.3f;", + CDTIME_T_TO_DOUBLE (lc->max), + max_bin, + CDTIME_T_TO_DOUBLE (lc->bin_width), + CDTIME_T_TO_DOUBLE (bin_width)); + } + memset (lc, 0, sizeof (*lc)); /* preserve bin width */