On Mon, 24 Nov 2008, Neil Gunton wrote:
I think the issue here is the large size of the directory tree itself -
simply traversing this seems to be a problem. I started off a du this
morning on that tree, at around 9am, and it's now after 12 midday and
the command is still not done yet. Meanwhile my iowait has doubled on
the server as a result.
Just a random thought... The O(n) directory search/traversal in
filesystems only hits you if you have directories with many many files in.
If your directories are like the one you sampled, with few items in, then
maybe you are thrashing one of the filesystem caches -- inodes, vnodes or
such -- while traversing the tree. I don't recall off-hand how you check
this, though looking at the output of iostat and vmstat would give you
some idea of where the traffic is in the VM and block IO subsystems.
Best wishes,
John
