iotop after 7.2 upgrde

[Tobbe]

Hello

after upgrade to 7.2 iotop fields SWAPIN and IO is unavailable.
i suspect this is related to the new kernel.

suggestions how to fix?

 

[Stoiko Ivanov]

i suspect this is related to the new kernel.

Hmm - sounds sensible - and I just checked - the values are not present here as well with the new kernel - however - this thread:
https://www.spinics.net/lists/kernel/msg4053632.html

pointed me to the new sysctl - and:

sysctl -w kernel.task_delayacct=1

fixed the issue for me - you can set it in /etc/sysctl.d/99-local.cf for example.

I hope this helps!

 

[Aleksej]

Actually, iotop shows "CONFIG_TASK_DELAY_ACCT not enabled in kernel, cannot determine SWAPIN and...."

Editing /etc/grub/default with
GRUB_CMDLINE_LINUX_DEFAULT="delayacct"
fixes this issue.

So, maybe have sense to enable it in kernel again? And post and update (or with new kernel)

 

[Alecz]

Is it possible to enable this while the system is running without requiring a reboot?

I tried:

 sysctl kernel.task_delayacct=1
 
 echo 1 > /proc/sys/kernel/task_delayacct
 
 sysctl -w kernel.task_delayacct=1

cat /proc/sys/kernel/task_delayacct
1

And while the output says kernel.task_delayacct = 1, iotop keeps giving:

CONFIG_TASK_DELAY_ACCT and kernel.task_delayacct sysctl not enabled in kernel, cannot determine SWAPIN and IO %

EDIT:
Important: while iotop did not work in the same terminal session, it worked in a separate session that had been opened before. (might work in a new session as well), because "this only affects the processes that fork after the setting change."

Also, this is the changed that decided "this stuff isn't actually used much":
https://git.kernel.org/pub/scm/linu.../?id=e4042ad492357fa995921376462b04a025dd53b6

I guess too few sysadmins iotop or similar.

 

[Impact]

I use this (iotop-c, actually, which has a convenient keyboard shortcut for it) all the time and it's in all my guests' kernel args. I wrote about it too.