From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 6 Sep 2018 11:18:51 +0300 From: Vladimir Davydov Subject: Re: [PATCH 8/8] vinyl: keep track of thread pool idle ratio Message-ID: <20180906081851.tlkeedihyfe5qoff@esperanza> References: <20180906074937.GH8205@chai> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180906074937.GH8205@chai> To: Konstantin Osipov Cc: tarantool-patches@freelists.org List-ID: On Thu, Sep 06, 2018 at 10:49:37AM +0300, Konstantin Osipov wrote: > * Vladimir Davydov [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? It is measured for entire pool - note that I divide the result by worker_count. E.g. if there were two workers and one of them were busy all the time between two last dumps while another were idle, idle_ratio would be 0.5.