Date: Fri, 16 Jun 95 11:39:48 MDT From: terry@cs.weber.edu (Terry Lambert) To: rashid@haven.ios.com (Rashid Karimov.) Cc: hackers@freebsd.org Subject: Re: 2.0.5R - misterious lockups (--MARK--?) Message-ID: <9506161739.AA12354@cs.weber.edu> In-Reply-To: <199506161320.JAA08612@haven.ios.com> from "Rashid Karimov." at Jun 16, 95 09:20:26 am
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> > > After the joy of working QUOTAs in 205R came first > > > problem: > > > system periodically locks up under 25-30 users load > > > in very weird way: > > > > Are you using quotas on more than one mounted FS? I heard there were > > problems with doing that. > > Yep ! > I have 'em on 5 FS'es - /var and 4 user partitions > > Any known cure ? Or at least the explanations where is > the problem ( well, if there were one , it would have been > fixed IMHO :( > > I absolutely need QUOTAs - that's the user server :(( > ~2.500 accounts You need to find out if that is indeed the problem by setting up a test case of only one mounted file system with quotas on. >From looking at the quota code, it looks like it may not take the dev_t field into accoun when computing quotas, which means that it doesn't use the right mount record to locate the quota file. So it locks entrancy across file systems, but doesn't compute transitive closure over the directed graph which is the set of locks held in all file systems. Really, it should per-fs lock to guarantee reentrancy. Probably this is a 10-15 line fix in the quota code alone, if someone spends the time working it out (I've just taken a quick pass through the code that does vonde-based I/O that the quota stuff uses, and I didn't see any obvious bugs). Terry Lambert terry@cs.weber.edu --- Any opinions in this posting are my own and not those of my present or previous employers.
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