Comment 403 for bug 620074

I determined main option:

Only this option helped to me:

# echo deadline > /sys/block/sda/queue/scheduler

I don't understand why. I have read many russian topics that a changing of scheduler doesn't help ... I don't think that only a changing of scheduler will help to me. But i only have changed the scheduler from cfq to deadline and 'dd' test now this:

# dd if=/dev/zero of=testfile.1gb bs=1M count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 13.7121 seconds, 76.5 MB/s

iowait sometime was only 80-90%.

Here my current setting:

# cat /proc/sys/vm/vfs_cache_pressure
100
# cat /sys/block/sda/queue/scheduler
noop anticipatory [deadline] cfq
# cat /sys/block/sda/queue/nr_requests
128

Now i will keep these setting and will watch there are a freezes or not.