From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Lehmann Subject: Re: write performance difference 3.18.21/4.2.1 Date: Fri, 25 Sep 2015 08:50:57 +0200 Message-ID: <20150925065057.GA2638@schmorp.de> References: <20150924175131.GC40291@jaegeuk-mac02> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sog-mx-1.v43.ch3.sourceforge.com ([172.29.43.191] helo=mx.sourceforge.net) by sfs-ml-2.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1ZfMqY-0007yr-KS for linux-f2fs-devel@lists.sourceforge.net; Fri, 25 Sep 2015 06:51:06 +0000 Received: from mail.nethype.de ([5.9.56.24]) by sog-mx-1.v43.ch3.sourceforge.com with esmtps (TLSv1:AES128-SHA:128) (Exim 4.76) id 1ZfMqX-0002XB-DO for linux-f2fs-devel@lists.sourceforge.net; Fri, 25 Sep 2015 06:51:06 +0000 Content-Disposition: inline In-Reply-To: <20150924175131.GC40291@jaegeuk-mac02> <20150924182836.GD40291@jaegeuk-mac02> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net To: Jaegeuk Kim Cc: linux-f2fs-devel@lists.sourceforge.net On Thu, Sep 24, 2015 at 11:28:36AM -0700, Jaegeuk Kim wrote: > One thing that we can try is to run the latest f2fs source in v3.18. > This branch supports f2fs for v3.18. Ok, please bear with me, the last time I built my own kernel was during the 2.4 timeframe, and this is a ubuntu kernel. What I did is this: git clone -b linux-3.18 git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git cd f2fs/fs/f2fs rsync -avPR include/linux/f2fs_fs.h include/trace/events/f2fs.h /usr/src/linux-headers-3.18.21-031821/. make -C /lib/modules/3.18.21-031821-generic/build/ M=$PWD modules modules_install I then rmmod f2fs/insmod the resulting module, and tried to mount my existing f2fs fs for a quick test, but got a null ptr exception on "mount": http://ue.tst.eu/e4628dcee97324e580da1bafad938052.txt Probably caused me not building a full kernel, but recreating how ubuntu build their kernels on a debian system isn't something I look forward to. > For example, if I can represent blocks like: [number of logs discussion] Thanks for this explanation - two logs doesn't look so bad, from a locality viewpoint (not a big issue for flash, but a big issue for rotational devices - I also realised I can't use dmcache as dmcache, even in writethrough mode, writes back all data after an unclean shutdown, which would positively kill the disk). Since whatever speed difference I saw with two logs wasn't big, you completely sold me on 6 logs, or 4 (especially if it seepds up the gc, which I haven't much tested yet). Two logs was merely a test anyway (the same with no_heap, I don't know what it does, but I thought it is worth a try, as metadata + data nearer together is better than having them at opposite ends of the log or so). -- The choice of a Deliantra, the free code+content MORPG -----==- _GNU_ http://www.deliantra.net ----==-- _ generation ---==---(_)__ __ ____ __ Marc Lehmann --==---/ / _ \/ // /\ \/ / schmorp@schmorp.de -=====/_/_//_/\_,_/ /_/\_\ ------------------------------------------------------------------------------