From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Tso Subject: Re: How git affects kernel.org performance Date: Mon, 8 Jan 2007 09:17:55 -0500 Message-ID: <20070108141755.GF32756@thunk.org> References: <45A08269.4050504@zytor.com> <45A083F2.5000000@zytor.com> <20070107085526.GR24090@1wt.eu> <20070107011542.3496bc76.akpm@osdl.org> <20070108030555.GA7289@in.ibm.com> <20070108125819.GA32756@thunk.org> <20070108134147.GB5291@linuxtv.org> <20070108135622.GD32756@thunk.org> <20070108135952.GF25857@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Johannes Stezenbach , Suparna Bhattacharya , Andrew Morton , Willy Tarreau , Linus Torvalds , "H. Peter Anvin" , git@vger.kernel.org, nigel@nigel.suspend2.net, "J.H." , Randy Dunlap , kernel list , webmaster@kernel.org, "linux-ext4@vger.kernel.org" Return-path: To: Pavel Machek Content-Disposition: inline In-Reply-To: <20070108135952.GF25857@elf.ucw.cz> Sender: git-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Mon, Jan 08, 2007 at 02:59:52PM +0100, Pavel Machek wrote: > Hi! > > > > Would e2fsck -D help? What kind of optimization > > > does it perform? > > > > It will help a little; e2fsck -D compresses the logical view of the > > directory, but it doesn't optimize the physical layout on disk at all, > > and of course, it won't help with the lack of readahead logic. It's > > possible to improve how e2fsck -D works, at the moment, it's not > > trying to make the directory be contiguous on disk. What it should > > probably do is to pull a list of all of the blocks used by the > > directory, sort them, and then try to see if it can improve on the > > list by allocating some new blocks that would make the directory more > > contiguous on disk. I suspect any improvements that would be seen by > > doing this would be second order effects at most, though. > > ...sounds like a job for e2defrag, not e2fsck... I wasn't proposing to move other data blocks around in order make the directory be contiguous, but just a "quick and dirty" try to make things better. But yes, in order to really fix layout issues you would have to do a full defrag, and it's probably more important that we try to fix things so that defragmentation runs aren't necessary in the first place.... - Ted