On Fri, Apr 25, 2014 at 1:52 PM, Jay Aurabind <jay.aurabind@gmail.com> wrote:
Hi,
My kernel is 3.13.0-24, ubuntu 14.04. I have an ext4 root partition, and I can see 2 threads (kworker,jbd2) periodically writing to hdd at about roughly (1,5) second interval.
I disabled journalling so that jbd2 is gone. Still, the kworker thread is bugging me. Is it really necessary for the system to work properly?
cat /proc/<PID>/stack of the kworker is:
[<ffffffff810846f1>] worker_thread+0x1d1/0x410 [<ffffffff8108b312>] kthread+0xd2/0xf0 [<ffffffff8172637c>] ret_from_fork+0x7c/0xb0 [<ffffffffffffffff>] 0xffffffffffffffff
It doesnt make any sense to me.
On tracing this kworker, I found this line:
kworker/u8:1-68 [000] d... 1135.724955: workqueue_queue_work: \ work struct=ffff8800701e00b8 function= \ ata_sff_pio_task workqueue=ffff880073e6f600 req_cpu=256 cpu=0
So it seems the function ata_sff_pio_task in drivers/ata/libata-sff.c#L1343 is being run. Why is it getting called periodically? Is it possible to suppress it ?
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. ALso, it could be the I/O scheduler too. Try to switch to noop and see if it change the situation -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com