[PATCH 8/8] vinyl: keep track of thread pool idle ratio

Konstantin Osipov kostja at tarantool.org
Thu Sep 6 10:49:37 MSK 2018

* Vladimir Davydov <vdavydov.dev at gmail.com> [18/09/04 20:59]:
> To understand whether the disk is fully utilized or can still handle
> more compaction load and make right decisions regarding transaction
> throttling, we need a metric that would report how much time worker
> threads spent being idle. So this patch adds two new metrics to global
> statistics, disk.dump_idle_ratio and compact_idle_ratio, which show how
> much time dump threads and compaction threads were idle, respectively.
> The metrics are updated using the following formula:
>                        idle_time
>   idle_ratio = --------------------------
>                dump_period * worker_count

I don't understand the formula. There can be many workers.
Is idle time measured per worker or per entire pool? 

If it is measured per entire pool, how is idle time calculated if
some workers are busy and some not?

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

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