Date: Tue, 20 Apr 1999 04:52:46 +0800 From: adrian@freebsd.org To: Arjan de Vet <Arjan.deVet@adv.iae.nl> Cc: freebsd-hackers@freebsd.org Subject: Re: Directories not VMIO cached at all! Message-ID: <19990419205247.28410.qmail@ewok.creative.net.au> In-Reply-To: Your message of "Mon, 19 Apr 1999 22:19:19 %2B0200." <199904192019.WAA05340@adv.iae.nl>
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Arjan de Vet writes: >In article <199904191650.JAA24137@vashon.polstra.com> John Polstra writes: > >>If I understand your description correctly, this fix could really >>benefit master CVSup servers such as freefall. Those servers >>typically have 8-12 running cvsupd processes, all doing tree walks >>over the same CVS repository and making a stat() call on every file. >> >>Do you think it would help? > >It helps to some extend I think. The Squid server I've been testing can >keep 32MB worth of directories cached after some tuning but because of >the enormous amount of reads and writes being done half of the >directories get removed from the cache after 5-10 minutes. We're >speaking about 750,000-1,000,000 files in 4096 directories in a >two-level hierarchy where 80% of the files is 9 KB or less in size. >B.t.w., the Squid people are working on a SquidFS which will not use >individual files anymore. Which is nice, but another method to fix this kind of problem (lots of memory used up to cache directory entries which really shouldn't be needed) is an inodefs - the namespace is pure inode only, and then you 'layer' stuff on top of it via stacking layers - so you'd write a squidfs stacking layer to give the virtual namespace squid uses. However, stacking layers are not quite functional yet (come on Eivind, we're all cheering here. :), and I don't think anyone would do this in the near future. If it happened, it would certinaly make applications like squid and news *fly*. Adrian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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