Re: [Jfs-discussion] Strange problem with JFS
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From: Jon N. <jne...@ja...> - 2004-12-18 06:08:55
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On Fri, 17 Dec 2004, Sonny Rao wrote: > On Thu, Dec 16, 2004 at 04:17:53PM -0600, John Goerzen wrote: > <snip> >> I noticed my problems during runs of updatedb (for locate). That >> process basically reads a bunch of directories, probably stats all the >> files, but never actually opens the files. (I think it runs find.) > >> I wonder if this has something to do with directories or inodes. >> >> I haven't lately noticed it with updatedb runs, but I have noticed it >> periodically when copying, or building ISO images or things like that. > > Yes, again this sounds similar to a problem someone reported a week or > two ago, where he had a directory with 500k files and was running find > on it. The symptoms will be that kswapd is running a lot and system > responsiveness will be very poor. Also, it's certainly possible that > some of your directorys will have very few files, but what's important > is the total number of inodes in memory, not any particular directory. > > You should look at the number of inodes incore at this point, and this > will give you an idea of whether this is the problem or not. Do this > by using either "slabtop" or looking at /proc/slabinfo and looking at > the number of slabs used for dentrys and inodes. > > If this is indeed the problem, one stopgap measuere on > 2.6.7 kernels > is to alter the value of /proc/sys/vm/vfs_cache_pressre upwards. I > would try values with different orders of magnitude, i.e. 1000, 10000, > 100000, etc. This should cause kswapd to be more aggressive in > eliminating slab objects, which means it will hold the dcache for less > time overall. Well, I'm not really sure what I'm looking for, but I did this: fstest -n 50 -f 10000 -s 2048 Then, in another terminal, I ran this find . | wc -l and from slaptop, sorted on cache size: 49396 49391 99% 0.81K 12349 4 49396K jfs_ip 46452 46228 99% 0.28K 3318 14 13272K radix_tree_node 13244 10512 79% 0.14K 473 28 1892K dentry_cache 9375 7382 78% 0.05K 125 75 500K buffer_head At this time the disk light is (for the last 5 minutes or more now) completely inactive (except for a very occasional blip). Looks like I cannot kill fstest or find (kill -9 has no effect). Both processes are in 'D+' mode. I got fstest (I'm pretty sure mine is old) at: http://samba.org/ftp/unpacked/junkcode/ What else can I do? -- Jon Nelson <jne...@ja...> |