SLUG Mailing List Archives
Re: [SLUG] Image rotation for some images taking hours too long.
- To: Michael Lake <mikel@xxxxxxxxxxxxxxxxx>
- Subject: Re: [SLUG] Image rotation for some images taking hours too long.
- From: Peter Chubb <peterc@xxxxxxxxxxxxxxxxxx>
- Date: Sun, 20 Apr 2008 21:13:42 +1000
- Cc: slug@xxxxxxxxxxx
- Organization: Gelato@UNSW
- User-agent: Wanderlust/2.15.5 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (Gojō) APEL/10.7 MULE XEmacs/21.4 (patch 21) (Educational Television) (x86_64-linux-gnu)
>>>>> "Michael" == Michael Lake <mikel@xxxxxxxxxxxxxxxxx> writes:
Michael> Questions: What is 'uninterruptable sleep' ? Anyhow pointers
Michael> on how I can speed things up. Why oh why might a few dozen
Michael> images / 200 take so long when others take 30 seconds?
Uninterruptible sleep is generally waiting for disk I/O -- either swap
-- a few bad sectors on the disc causing timeouts and retries
(check dmesg output)
-- you've gone over a boundary that means mogrify is using
enough memory to need to swap (although I can see no sign
of swap usage in your `top' snapshot)
-- Beginning to run out of disk space meaning that the
filesystem has to do a lot of work to allocate space for
temporary files or output files.
-- Disc fragmentation for those files, meaning lots of seek
activity to read them.
Try copying the problematic files to a different filesystem and running
your rotate again.
Dr Peter Chubb http://www.gelato.unsw.edu.au peterc AT gelato.unsw.edu.au
http://www.ertos.nicta.com.au ERTOS within National ICT Australia