Re: [PATCH 17/18] vinyl: set quota timer period to 100 ms

[Konstantin Osipov <kostja@tarantool.org>]

* Vladimir Davydov <vdavydov.dev@gmail.com> [18/08/16 23:03]:
> Currently, it's 1 second, which is OK for calculating watermark, but
> too long for throttling (think of latency of 1 seconds that would be
> introduced by throttling if such timeout were used).

1) I think the timer period should self-adjust based on the amount
   of available quota.

2) We narrowed down the problem to throttling only.
   We never do anticipatory dump/compaction today.  Let's design a
   system which swings the pendulum both ways - not only throttles
   the client when the load is high but performs an anticipatory
   dump/compaction when the load is low. See for example
   https://github.com/tarantool/tarantool/issues/3225

   In other words, I think we should not only enable "stalls" in
   the timer callback when the write stream is strong, but
   trigger compaction when the write stream is thin. Unfortunately
   we do not collect read statistics per lsm as a secondary
   indicator of compaction priority, so we may only trigger
   compaction based simply on the number of levels, but never the
   less.


-- 
Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.io - www.twitter.com/kostja_osipov