debuging high IO wait under linux

To do that you can use block IO debugging capability of Linux kernel.

echo 1 > /proc/sys/vm/block_dump

After this run

dmesg | egrep "READ|WRITE|dirtied" |  awk '{print $1}'|  sort | uniq -c | sort -rn | head

   1583 kjournald(2764):
    545 kjournald(1023):
     48 beam.smp(21021):
     47 sendmail(20992):
     28 crond(20974):

Now disable the block IO debugging

echo 0 > /proc/sys/vm/block_dump

Публикувано в linux