From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 6 Jul 2007 17:57:49 +0200 From: =?utf-8?B?SsO2cm4=?= Engel Subject: Re: vm/fs meetup details Message-ID: <20070706155748.GC846@lazybastard.org> References: <20070705040138.GG32240@wotan.suse.de> <468D303E.4040902@redhat.com> <137D15F6-EABE-4EC1-A3AF-DAB0A22CF4E3@oracle.com> <20070705212757.GB12413810@sgi.com> <468D6569.6050606@redhat.com> <20070706022651.GG14215@wotan.suse.de> <20070706100110.GD12413810@sgi.com> <20070706102623.GA846@lazybastard.org> <20070706134201.GL31489@sgi.com> <20070706095214.1ac9da94@think.oraclecorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20070706095214.1ac9da94@think.oraclecorp.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Chris Mason Cc: David Chinner , =?utf-8?B?SsODwrZybg==?= Engel , Nick Piggin , Rik van Riel , Zach Brown , Anton Altaparmakov , Suparna Bhattacharya , Christoph Hellwig , Hugh Dickins , Jared Hulbert , "Martin J. Bligh" , Trond Myklebust , Neil Brown , Miklos Szeredi , Mingming Cao , Linux Memory Management List , linux-fsdevel@vger.kernel.org, Evgeniy Polyakov , Steven Whitehouse , Dave McCracken , Peter Zijlstra List-ID: On Fri, 6 July 2007 09:52:14 -0400, Chris Mason wrote: > On Fri, 6 Jul 2007 23:42:01 +1000 David Chinner wrote: > > > Hmmm - I guess you could use it for writeback ordering. I hadn't > > really thought about that. Doesn't seem a particularly efficient way > > of doing it, though. Why not just use multiple address spaces for > > this? i.e. one per level and flush in ascending order. Interesting idea. Is it possible to attach several address spaces to an inode? That would cure some headaches. > At least in the case of btrfs, the perfect order for sync is disk > order ;) COW happens when blocks are changed for the first time in a > transaction, not when they are written out to disk. If logfs is > writing things out some form of tree order, you're going to have to > group disk allocations such that tree order reflects disk order somehow. I don't understand half of what you're writing. Maybe we should do another design session on irc? At any rate, logfs simply writes out blocks. When it is handed a page to write, the corresponding block is written. Allocation happens at writeout time, not earlier. Each written block causes a higher-level block to get changed, so that is written immediatly as well, until the next higher level is the inode. I would like to instead just dirty the higher-level block, so that multiple changes can accumulate before indirect blocks are written. And I have no idea how transactions relate to all this. > But, the part where we toss leaves first is definitely useful. Shouldn't LRU ordering already do that. I can even imagine cases when leaves should be tossed last and LRU ordering would dtrt. JA?rn -- The competent programmer is fully aware of the strictly limited size of his own skull; therefore he approaches the programming task in full humility, and among other things he avoids clever tricks like the plague. -- Edsger W. Dijkstra -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org