From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 6 Feb 2019 16:43:41 +0300 From: Konstantin Osipov Subject: Re: [tarantool-patches] Re: [PATCH 7/9] vinyl: randomize range compaction to avoid IO load spikes Message-ID: <20190206134341.GB24382@chai> References: <44f34fbaf09af5d1054f2e4843a77e095afe1e71.1548017258.git.vdavydov.dev@gmail.com> <20190122125458.cutoz5rtfd2sb6el@esperanza> <20190205173958.GG6811@chai> <20190206085302.3xzjz2udfvdin5ld@esperanza> <20190206104419.GD19953@chai> <20190206105244.c4gkhb3xsn2pkqmp@esperanza> <20190206110609.GA24382@chai> <20190206114905.qq6wwcdexal4gy3j@esperanza> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190206114905.qq6wwcdexal4gy3j@esperanza> To: Vladimir Davydov Cc: tarantool-patches@freelists.org List-ID: * Vladimir Davydov [19/02/06 14:53]: > We know which run is last. Provided the workload is stable, i.e. have > stopped growing its dataset, it will be roughly the same. Besides, the > last level run size changes only on major compaction, which is > infrequent. After a major compaction, it's OK to use a different first > level size - the point is in order not to break LSM algorithm, we have > to maintain stable level sizing between major compactions. The problem is that you can't use the last level as-is. You need a divider, e.g. dumps_per_compaction, which is meaningless until the first major compaction has happened. -- Konstantin Osipov, Moscow, Russia, +7 903 626 22 32 http://tarantool.io - www.twitter.com/kostja_osipov