[debian-knoppix] cloop 1.02 available for testing on SMP machines
Hello everyone,
Due to a kernel bug in 2.4.22 *) that almost immediately causes a IO
freeze on the io request wait queue, I had to work on cloop again.
Version 1.02 does not use the asynchronous io request wait queue
anymore, and has been successfully tested on a few single processor
machines, but I would like to make sure it also works on SMP machines
(the code currently uses no spinlocks at all).
*) Actually, the bug has been there for a long time, but so far has only
been observed under high disk io load. Since 2.4.22, the io request
queue deadlock just appears very fast and reproducible, on all tested
machines. As far as debugging was possible, the bug is not directly
related to cloop, but cloop <= 1.02 can trigger it under certain
circumstances.
If anyone would like to test cloop 1.02 with Kernel 2.4.22 on a SMP
machine, the source is available here:
http://developer.linuxtag.net/knoppix/sources/cloop_1.02-1.tar.gz
Recommended test (don't do this on a production machine, and be aware
that you may have to press the reset button if anything goes wrong):
Let's assume your cloop images are under /tmp/image1...4
1. Mounting multiple cloop images
insmod cloop
for i in 1 2 3 4; do
mknod /dev/cloop$i b 240 $i
losetup /dev/cloop$i /tmp/image$i
mkdir -p /mnt/cloop$i
mount -t iso9660 -r /dev/cloop$i /mnt/cloop$i
done
2. Start the stress-test
for i in 1 2 3 4; do
tar cpPf - /mnt/cloop$i | dd of=/dev/null &
sleep 10
tar cpPf - /mnt/cloop$i | dd of=/dev/null &
done
3. Watch results (dmesg, top)
Looking forward to test results (or hints about missing spinlocking code
in compressed_loopback.c).
-Klaus Knopper
PS: If you don't understand what any of this means, it does not apply to
you, and you can safely ignore this mail. ;-)
--
Klaus Knopper Technical Solutions & Finances
knopper@linuxtag.org http://www.linuxtag.org/
Phone +49-(0)631-3109371 Fax +49-(0)631-3109372
LinuxTag 2004 - Europes largest Linux Expo Where .com meets .org
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