On Tue, 15 Feb 2011 16:12:42 GMT, Paul Vixie said:
From: Valdis(_dot_)Kletnieks(_at_)vt(_dot_)edu Date: Tue, 15 Feb 2011 10:42:34 -0500 00.21 versus 33.47? I'd really investigate hot/cold cache effects there. If you "just" moved it to UFS, a copy is probably still in cache. Any way to flush the in-memory file cache on your box and try again?there isn't but freebsd only has one buffer, inode, and metadata cache, it's not per-filesystem. and i ran those scans back to back, so if there are caching effects going on then the second and third scans ought to be equally fast for the two file systems. it may be that rather than a fragmentation problem there's a VFS flagging problem where ZFS is advising the buffer cache not to keep copies of the metadata. either way i'm going to take a look at geom/gvinum. i don't mind a write penalty for raid6/raidz2 but a read penalty of this many orders of magnitude is just too whacky.
Well, a quick look indicates that 00.21 can't *possibly* be off the disk for 4,000+ files, unless you have a disk system that can return 20,000 inode reads for stat() calls per second (not counting all the *other* I/O such as actually reading the file :) Unfortunately, I understand Linux innards better than FreeBSD, so you're on your own on this one. ;)
pgp0xNq2qWCj5.pgp
Description: PGP signature
_______________________________________________ Nmh-workers mailing list Nmh-workers(_at_)nongnu(_dot_)org http://lists.nongnu.org/mailman/listinfo/nmh-workers