Date: Thu, 3 Nov 2005 01:17:51 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Ivan Voras <ivoras@fer.hr> Cc: freebsd-fs@freebsd.org Subject: Re: ext2 large_file Message-ID: <20051103011024.R7399@epsplex.bde.org> In-Reply-To: <20051101114150.X90580@geri.cc.fer.hr> References: <20051030183340.B19470@geri.cc.fer.hr> <46D894BD-16E0-4CBA-B40A-EEBAAC2547D2@classicalguitar.net> <20051031191139.J38757@delplex.bde.org> <20051031160354.G67271@geri.cc.fer.hr> <20051101042444.K40281@delplex.bde.org> <20051031201719.S68800@geri.cc.fer.hr> <20051101141726.W41623@delplex.bde.org> <20051101114150.X90580@geri.cc.fer.hr>
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On Tue, 1 Nov 2005, Ivan Voras wrote: > On Tue, 1 Nov 2005, Bruce Evans wrote: > >> On Mon, 31 Oct 2005, Ivan Voras wrote: > [for ext2fs under FreeBSD] >> first few cylinder groups full and the rest unused, where Linux would >> use all the groups fairly evenly. > > Not so good. I suppose this is not easaly fixable? Not very easily, but not very uneasily either. We can either obtain a block allocator from NetBSD (I think it is similar to ffs's, but specialized to ext2fs), or use the current Linux allocator (I think we have an old version already -- ISTR a comment saying that it is used for checking only). >> - ext2fs is about twice as slow as the other 2 (worse for non-async >> writes). >> It is mostly because the block size is very small, and although this >> only necessarily costs extra CPU to do clustering, FreeBSD is optimized >> for ffs's default block size and does pessimal things with ext2fs's >> smaller sizes. > > These effects are also very noticable with NTFS (default block size=4096 for > all/most partition sizes) and FAT32 on smaller drives (where bs=4096 fits FAT > in 8MB). 4K isn't too bad, except possibly on arches with a page size of 8K -- see my benchmark output for msdosfs. Clustering is certainly required to get good results for large files. Bruce
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