[tarantool-patches] Re: [PATCH v2 02/11] vinyl: factor load regulator out of quota

[Konstantin Osipov <kostja@tarantool.org>]

* Vladimir Davydov <vdavydov.dev@gmail.com> [18/09/28 21:00]:
> Turned out that throttling isn't going to be as simple as maintaining
> the write rate below the estimated dump bandwidth, because we also need
> to take into account whether compaction keeps up with dumps. Tracking
> compaction progress isn't a trivial task and mixing it in a module
> responsible for resource limiting, which vy_quota is, doesn't seem to be
> a good idea. Let's factor out the related code into a separate module
> and call it vy_regulator. Currently, the new module only keeps track of
> the write rate and the dump bandwidth and sets the memory watermark
> accordingly, but soon we will extend it to configure throttling as well.
> 
> Since write rate and dump bandwidth are now a part of the regulator
> subsystem, this patch renames 'quota' entry of box.stat.vinyl() to
> 'regulator'. It also removes 'quota.usage' and 'quota.limit' altogether,
> because memory usage is reported under 'memory.level0' while the limit
> can be read from box.cfg.vinyl_memory, and renames 'use_rate' to
> 'write_rate', because the latter seems to be a more appropriate name.
> 
> Needed for #1862

It's all good except the name. The name is a bit more academic,
generic and long than we both prefer. Other names to consider:
vy_pressure_valve, vy_back_pressure, or simply vy_valve, vy_load_valve,
vy_load_control, vy_rate_control, vy_bandwidth, (I think if we add
more names to the table we will be able to find a good one).

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