From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: Re: dm-cache performance behaviour Date: Wed, 6 Apr 2016 04:13:49 -0800 Message-ID: <20160406121349.GA11587@kmo-pixel> References: <20160405071253.GB27444@suselix.suse.de> <570378FC.3030701@redhat.com> <20160405140507.GG27444@suselix.suse.de> <20160405161226.GA17811@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pa0-f49.google.com ([209.85.220.49]:34867 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932447AbcDFMNx (ORCPT ); Wed, 6 Apr 2016 08:13:53 -0400 Content-Disposition: inline In-Reply-To: <20160405161226.GA17811@redhat.com> Sender: linux-bcache-owner@vger.kernel.org List-Id: linux-bcache@vger.kernel.org To: Mike Snitzer Cc: Andreas Herrmann , Zdenek Kabelac , linux-block@vger.kernel.org, dm-devel@redhat.com, linux-bcache@vger.kernel.org On Tue, Apr 05, 2016 at 12:12:27PM -0400, Mike Snitzer wrote: > Anyway, as Zdenek effectively: said dm-cache isn't a writecache. If you > need a writecache then bcache is the only option as of now. Though > there is an emerging DM writecache target that has stalled but can be > revisited, see: > http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/log/?h=writecache bcache is still more than that, it's a combined read/writeback cache :) much like how today we only have one pagecache for both read caching and write caching. Main trick is you need a pretty sophisticated btree to pull that off with good performance.