From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 23 Aug 2018 23:58:15 +0300 From: Konstantin Osipov Subject: Re: [tarantool-patches] Re: [PATCH 18/18] vinyl: throttle tx rate if dump does not catch up Message-ID: <20180823205815.GA30863@chai> References: <20180823205443.GF24711@chai> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180823205443.GF24711@chai> To: Vladimir Davydov Cc: tarantool-patches@freelists.org List-ID: * Konstantin Osipov [18/08/23 23:55]: > * Vladimir Davydov [18/08/16 23:03]: > > If the rate at which transactions are ready to write to the database is > > greater than the dump bandwidth, memory will get depleted before the > > last dump is complete and all newer transactions will have to wait until > > the dump has been completed, which may take seconds or even minutes: > > Why are you limiting the rate only during a dump? What about > compaction throughtput? Write amplification from compaction is > 10x+ times higher than from dump, compaction is actually the main > consumer of disk bandwidth. Shouldn't you throttle writes when > write bandwidth is higher than write amplification/disk bandwidth? if (disk bandwidth/write amplification > write bandwidth) throttle writes; else expedite compaction -- Konstantin Osipov, Moscow, Russia, +7 903 626 22 32 http://tarantool.io - www.twitter.com/kostja_osipov