Mark Callaghan 993543d1be Add rate_delay_limit_milliseconds ... Summary: This adds the rate_delay_limit_milliseconds option to make the delay configurable in MakeRoomForWrite when the max compaction score is too high. This delay is called the Ln slowdown. This change also counts the Ln slowdown per level to make it possible to see where the stalls occur. From IO-bound performance testing, the Level N stalls occur: * with compression -> at the largest uncompressed level. This makes sense because compaction for compressed levels is much slower. When Lx is uncompressed and Lx+1 is compressed then files pile up at Lx because the (Lx,Lx+1)->Lx+1 compaction process is the first to be slowed by compression. * without compression -> at level 1 Task ID: #1832108 Blame Rev: Test Plan: run with real data, added test Revert Plan: Database Impact: Memcache Impact: Other Notes: EImportant: - begin *PUBLIC* platform impact section - Bugzilla: # - end platform impact - Reviewers: dhruba Reviewed By: dhruba Differential Revision: https://reviews.facebook.net/D9045		2013-03-04 07:41:15 -08:00
..
leveldb	Add rate_delay_limit_milliseconds	2013-03-04 07:41:15 -08:00