On Tue, 15 Feb 2011 16:12:42 GMT, Paul Vixie said: > > From: [email protected] > > 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. ;)
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