From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx02.extmail.prod.ext.phx2.redhat.com [10.5.110.26]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 5CC0F19808 for ; Fri, 19 Oct 2018 20:54:32 +0000 (UTC) Received: from mr013msb.fastweb.it (mr013msb.fastweb.it [85.18.95.104]) by mx1.redhat.com (Postfix) with ESMTP id DA77A76554 for ; Fri, 19 Oct 2018 20:54:28 +0000 (UTC) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Date: Fri, 19 Oct 2018 22:54:26 +0200 From: Gionatan Danti In-Reply-To: References: <06b65c62-8ca2-0d29-b98d-1a1585141f81@redhat.com> <8ecbd3c8-4819-9ff2-40b1-315e6ae03c97@izyk.ru> <36f0f734-c49f-eaf9-7ff5-8aedfd7345b3@redhat.com> <707aafdc-cfd2-3bdd-13bb-1bfdc08c6ad9@assyoma.it> Message-ID: <17a367c7043400e4890738b00afcb011@assyoma.it> Subject: Re: [linux-lvm] =?utf-8?q?Why_doesn=27t_the_lvmcache_support_the_disc?= =?utf-8?q?ard_=28trim=29_command=3F?= Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: LVM general discussion and development Cc: Ilia Zykov Il 19-10-2018 15:08 Zdenek Kabelac ha scritto: > Hi > > It's rather about different workload takes benefit from different > caching approaches. > > If your system is heavy on writes - dm-writecache is what you want, > if you mostly reads - dm-cache will win. > > That's why there is dmstats to also help identify hotspots and overal > logic. > There is nothing to win always in all cases - so ATM 2 different > targets are provided - NVDIMMs already seems to change game a lot... > > dm-writecache could be seen as 'extension' of your page-cache to held > longer list of dirty-pages... > > Zdenek Thanks for these information. Reading a bit the commit which provide dm-writeback, it seems a sort of "L2 pagecache", right? It should be *very* interesting for use with NVDIMMs and/or fast NVME devices... Regards. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8