fs/bcachefs/time_stats.h

1 /* SPDX-License-Identifier: GPL-2.0 */
3  * bch2_time_stats - collect statistics on events that have a duration, with nicely
6  * - percpu buffering of event collection: cheap enough to shotgun
10  *  - number of events
11  *  - maximum event duration ever seen
12  *  - sum of all event durations
13  *  - average event duration, standard and weighted
14  *  - standard deviation of event durations, standard and weighted
18  * deviation and weighted standard deviation, to give an efficient-to-compute
19  * view of current behaviour versus. average behaviour - "did this event source
27 #include <linux/sched/clock.h>
41 const struct time_unit *bch2_pick_time_units(u64 ns);
44  * quantiles - do not use:
46  * Only enabled if bch2_time_stats->quantiles_enabled has been manually set - don't
100 	return stats->have_quantiles  in time_stats_to_quantiles()
101 		? &container_of(stats, struct bch2_time_stats_quantiles, stats)->quantiles  in time_stats_to_quantiles()
109  * time_stats_update - collect a new event being tracked
111  * @stats	- bch2_time_stats to update
112  * @start	- start time of event, recorded with local_clock()
114  * The end duration of the event will be the current time
122  * track_event_change - track state change events
124  * @stats	- bch2_time_stats to update
125  * @v		- new state, true or false
132 	if (v != !!stats->last_event_start) {  in track_event_change()
134 			bch2_time_stats_update(stats, stats->last_event_start);  in track_event_change()
135 			stats->last_event_start = 0;  in track_event_change()
137 			stats->last_event_start = local_clock() ?: 1;  in track_event_change()
151 	bch2_time_stats_exit(&statq->stats);  in bch2_time_stats_quantiles_exit()
155 	bch2_time_stats_init(&statq->stats);  in bch2_time_stats_quantiles_init()
156 	statq->stats.have_quantiles = true;  in bch2_time_stats_quantiles_init()
157 	memset(&statq->quantiles, 0, sizeof(statq->quantiles));  in bch2_time_stats_quantiles_init()