Date: Wed, 29 Dec 2010 14:18:01 -0800 From: Chris Peiffer <bsdlists@cabstand.com> To: freebsd-fs@freebsd.org Subject: how big can kern.maxvnodes get? Message-ID: <20101229221801.GA48661@cabstand.com>
next in thread | raw e-mail | index | archive | help
I have a backend server running 8-2-PRERELEASE with lots of independent files that randomly grow and then get truncated to zero. (Think popserver.) Roughly 2.5 million inodes on each of 4 Intel SSD disks. 24 gb of RAM in the system. I want to maximize the buffer cache in RAM. I doubled kern.maxvnodes to 942108 and reads/second went down and memory use went up, (as I expected) but right now there's still about 15g RAM marked as free. vfs.numvnodes crept up to 821704 and has hovered there. The file sizes range to 1 mb but most are in the range 0-10k. Since the server operations are so simple kern.openfiles hovers in the range 100-200. Obviously, all things being equal I'd like to give the filesystem buffer cache access to that free RAM by allowing more vnodes to stay cached. Can I increase kern.maxvnodes by another factor of 2? more? Are there any known problems with stepping it up, besides general memory exhaustion? With so much free RAM I'd like to turn the dial a little bit but I wonder if there are other linked things I should watch out for. Thanks. Here are some lines from vmstat -z that might be relevant: ITEM SIZE LIMIT USED FREE REQUESTS FAILURES VNODE: 472, 0, 779555, 69229, 163219829, 0 VNODEPOLL: 112, 0, 2, 64, 4, 0 S VFS Cache: 108, 0, 761856, 63606, 504696076, 0 L VFS Cache: 328, 0, 0, 228, 300, 0
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20101229221801.GA48661>