Kworker and jbd2 constantly writing to hdd

[jay.aurabind@gmail.com (Jay Aurabind)]

On Friday 25 April 2014 05:48 PM, Mulyadi Santosa wrote:
> 
> 
> Could it be a power management system trying to spin down your disk to
> save power?
> 
> Try to alter the power management variable from your desktop
> environment settings. Try to make it less aggresive.

Tried setting APM to 254, so as not to attempt a spin down, but no
change in the situation. But even if its the system trying to spin down,
would it get listed as a write operation? Isnt it supposed to be an
ioctl ? Does iotop consider ioctls as a write ? Its man page doesnt
mention anything about ioctls.

> 
> 
> ALso, it could be the I/O scheduler too. Try to switch to noop and see
> if it change the situation
> 

Under noop, deadline and cfq, the situation remains the same. Dont have
any other schedulers.

The kworker I mentioned was spotted from the output of iotop -o. I kept
"watching" /proc/meminfo while kworker was popping up. I found that even
though the same kworker showed up periodically at 1 second, meminfo's
"dirty" entry was getting modified only at about 45 seconds, with 8KB,
and subsequently after 1 minute, dirty would roll back to zero,
(probably indicating a real disk write?).

Iotop says it reports acutal I/O happening, and this seems consistent
with the above observation. But in reality, my HDD indicator is blinking
at 1 second, synchronous to kworker. Does the hdd indicator blink under
any circumstances other than a read or write? BTW its a light blink, not
a strong one like when we do some serious I/O. Can you please do an
"iotop -o" and see if you also have the same kworker popping up?


Thanks and Regards,
Jay

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