Commit Graph

2 Commits

Author SHA1 Message Date
sdong
fb9811ee9b Add a perf context level that doesn't measure time for mutex operations
Summary: Timing mutex operations can impact scalability of the system. Add a new perf context level that can measure time counters except for mutex.

Test Plan: Add a new unit test case to make sure it is not set.

Reviewers: IslamAbdelRahman, rven, kradhakrishnan, yhchiang, anthony

Reviewed By: anthony

Subscribers: MarkCallaghan, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D53199
2016-01-25 14:45:03 -08:00
Mike Kolupaev
ec7a944360 more times in perf_context and iostats_context
Summary:
We occasionally get write stalls (>1s Write() calls) on HDD under read load. The following timers explain almost all of the stalls:
 - perf_context.db_mutex_lock_nanos
 - perf_context.db_condition_wait_nanos
 - iostats_context.open_time
 - iostats_context.allocate_time
 - iostats_context.write_time
 - iostats_context.range_sync_time
 - iostats_context.logger_time

In my experiments each of these occasionally takes >1s on write path under some workload. There are rare cases when Write() takes long but none of these takes long.

Test Plan: Added code to our application to write the listed timings to log for slow writes. They usually add up to almost exactly the time Write() call took.

Reviewers: rven, yhchiang, sdong

Reviewed By: sdong

Subscribers: march, dhruba, tnovak

Differential Revision: https://reviews.facebook.net/D39177
2015-06-02 02:07:58 -07:00