[ILUG] What process is generating disk I/O

[Stephen Brooks]

Kenn Humborg wrote:
>>> Kenn Humborg wrote:
>>>> Running vmstat 1 on a machine shows me a certain amount of block I/O.
>>>>
>>>> But, short of strace-ing everything running on the machine, how can
>>>> I determine which processes are generating this I/O?
>>>>
>>>> lsof will show me open files, but that doesn't help much.
>>> echo 1 > /proc/sys/vm/block_dump
>>> tail -f /var/log/debug
>> OK - that's a good starting point.  I suppose a better approach
>> might be to fire the kern.debug messages to syslog on another
>> machine so that syslog I/O doesn't cause a feedback loop
>> (process writes to block, kernel writes debug message, syslog
>> writes to /var/log/debug, kernel writes debug message, etc...).	
> 
> Not really as useful as I expected, unfortunately.  It's easy enough
> to see who is reading blocks, but all the writes are attributed to
> kjournald or pdflush.
> 
> Ah well...
> 

If they're the processes being flagged I'd suggest the writes are being 
caused by atime on files and diratime updates on directories creating 
dirty inodes.  Look at "noatime,nodiratime" mount options.

-- 
Stephen Brooks <stephen at lincor.com>      Digital Depot, Thomas Street
Senior Software Engineer                            Dublin 8, Ireland
Lincor Solutions Ltd.                          Ph: +353 (0) 1 4893683