Date: Wed, 7 Jul 1999 16:55:28 -0700 (PDT) From: Julian Elischer <julian@whistle.com> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: David Greenman <dg@root.com>, freebsd-hackers@FreeBSD.ORG, freebsd-current@FreeBSD.ORG Subject: Re: Heh heh, humorous lockup Message-ID: <Pine.BSF.3.95.990707165417.23943X-100000@current1.whistle.com> In-Reply-To: <199907072323.QAA94794@apollo.backplane.com>
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On Wed, 7 Jul 1999, Matthew Dillon wrote: > :> limit ought to work for a 4G machine > :> > :> Since most of those news files were small, I think Kirk's news test code > :> is pretty much the worse case scenario as far as vnode allocation goes. > : > : Well, I could possibly live with 256MB, but the vnode/fsnode consumption > :seems to be getting a bit silly in the memory overhead department, even for > :machines with 4GB of RAM. It seems like there needs to be fewer of them > :and/or they need to go on a diet. > : > :-DG > : > :David Greenman > > Well, the problem occurs because the system has sufficient memory to keep > the underlying VM object around. The current vnode code will not place > a vnode on the free list until the underlying VM object goes away. The > 60MB worth of KVM being used to hold vnodes is supporting 1GB worth > of cached VM pages ( associated with small files, that is ). So even > though the numbers look strange, it does seem to scale. > > In order to turn the maxvnodes sysctl into a harder limit, the vnode > allocation & freeing code would have to be reworked some. Right now > vnodes are not placed back onto the free list until their underlying > VM objects go away. We would need to make the vnode lists (which are > headed by mount table entries) LRU and then attempt to reuse the vnodes > that way, destroying the underlying VM object when necessary. > > Alternatively we can try to make the vnode structure smaller, or we > could try to decouple the vnode from the VM object and instead reference > the VM object by inode. All I can say to that: Yuch. I'd rather just > bump up the KVM. or do what Kirk wants to do and merge the VM and Vnode structures I belive the UVM does a bit in this direction due to kirk's influence. julian > > -Matt > Matthew Dillon > <dillon@backplane.com> > > > > To Unsubscribe: send mail to majordomo@FreeBSD..org > with "unsubscribe freebsd-hackers" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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