Date: Sun, 27 Mar 2005 20:48:44 -0800 From: Julian Elischer <julian@elischer.org> To: Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-fs@freebsd.org Subject: Re: UFS Subdirectory limit. Message-ID: <42478CAC.10305@elischer.org> In-Reply-To: <17693.1111874886@critter.freebsd.dk> References: <17693.1111874886@critter.freebsd.dk>
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Poul-Henning Kamp wrote: > In message <20050326213048.GA33703@VARK.MIT.EDU>, David Schultz writes: > >>On Fri, Mar 25, 2005, Scott Long wrote: >> >>>David Schultz wrote: >>> >>>>On Sat, Mar 26, 2005, David Malone wrote: >>>> >>>> >>>>>There was a discussion on comp.unix.bsd.freebsd.misc about two weeks >>>>>ago, where someone had an application that used about 150K >>>>>subdirectories of a single directory. They wanted to move this >>>>>application to FreeBSD, but discovered that UFS is limited to 32K >>>>>subdirectories, because UFS's link count field is a signed 16 bit >>>>>quantity. Rewriting the application wasn't an option for them. > > > Has anybody here wondered how much searching a 150K directory would > suck performance wise ? > > I realize that with dir-hashing and vfs-cache it is not as bad as it > used to be, but I still think it will be unpleasant performance wise. We have a reason (*) to have 300000 entries in a directory.. once the dirhash cache size was made big enough, performance was acceptable. (*) (we didn't want to but had to for "a while until it's fixed") >
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