From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ryusuke Konishi Subject: Re: How does NILFS2 handle directory management Date: Fri, 11 Sep 2009 13:13:49 +0900 (JST) Message-ID: <20090911.131349.105189468.ryusuke@osrg.net> References: <20090910192619.GA1263@heethoofdje.13thmonkey.org> <20090911.102118.69189169.ryusuke@osrg.net> <873a6u16qy.wl%jir@sekiba.com> Reply-To: NILFS Users mailing list Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <873a6u16qy.wl%jir-27yqGEOhnJbQT0dZR+AlfA@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: users-bounces-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org Errors-To: users-bounces-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org To: users-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org, jir-hfpbi5WX9J54Eiagz67IpQ@public.gmane.org On Fri, 11 Sep 2009 12:48:37 +0900, Jiro SEKIBA wrote: > Hi > > As far as I see, nilfs2 directory management is based on ext2. > ext3 has same format as ext2, but file creation is faster than ext2. > http://plaza18.mbn.or.jp/~moriban/linux/img/FileSystemBenchmarkResults-01-03.png > # There may be more reliable benchmark result, but I cound't find it. > > So I think it would be worth to try porting ext3 code to nilfs2 > to improve file creation. Isn't it? Yeah, it sounds nice. The approach seems to be able to avoid both problems I mentioned. Thanks, Ryusuke Konishi > > thanks, > > regards, > -- > Jiro SEKIBA > > At Fri, 11 Sep 2009 10:21:18 +0900 (JST), > Ryusuke Konishi wrote: > > > > Hi Prasenjit Giri, and Reinoud, > > On Thu, 10 Sep 2009 21:26:19 +0200, Reinoud Zandijk > > Hi Prasenjit Giri, > > > > > > On Fri, Sep 11, 2009 at 12:46:04AM +0530, Prasenjit Giri wrote: > > > > Even after looking through various sites, forums, mailing lists I could not > > > > uncover the present directoy management of NILFS2. > > > > > > > > As I see a B-tree directory management in your long term to do list, it > > > > would be really nice if someone would ought to share the information > > > > regarding the present directory management of NILFS2 > > > > > > Currently directories are recorded just as a sequential file but not filled > > > with user data but with dirent entries in their blocks like ext2fs does. > > > Nothing special about that :) > > > > > > I dont know if b+tree directory management would be preferable though. With > > > some smart caching all directory operations can be made O(1) anyway. > > > > > > With regards, > > > Reinoud Zandijk > > > > Yes, directory is a file and it's already managed with b-tree like > > other files. However, the current directory design is not O(log n), > > and is actually slow especially for file creation. > > > > So, it leaves room for considering the true "b-tree directory > > management". > > > > OTOH, the replacement has the following points to notice: > > > > 1) It may complicate the log writer. > > > > The current log writer is designed on the basis that every data > > and meta data is a file. In NILFS, inodes, segment usage state, > > and checkpoints, are managed with correponding meta-data files. > > > > The true "b-tree directory management" may break this uniformity. > > > > 2) A disk format change is required. > > (We can deem this a trade-off at this stage) > > > > This may be a -v3 material. But anyway, patch proposals are welcome. > > > > Thank you, > > Ryusuke Konishi > > _______________________________________________ > > users mailing list > > users-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org > > https://www.nilfs.org/mailman/listinfo/users > > > > > > > > > _______________________________________________ > users mailing list > users-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org > https://www.nilfs.org/mailman/listinfo/users