Ubuntu
powertop package

powertop suggests "increase the VM dirty writeback time from 5.00 to 15 seconds" repeatedly

Bug #137602 reported by Alan Pope 🍺🐧🐱 🦄
6
Affects Status Importance Assigned to Milestone
powertop (Ubuntu)
Invalid
Undecided
Unassigned

Bug Description

Binary package hint: powertop

Amongst other useful things to do, powertop suggests:-

Suggestion: increase the VM dirty writeback time from 5.00 to 15 seconds with:
  echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
This wakes the disk up less frequenty for background VM activity

 Q - Quit R - Refresh W - Increase Writeback time

If I press W it goes away then comes back a few seconds later.

Revision history for this message
Alan Pope 🍺🐧🐱 🦄 (popey) wrote :
Revision history for this message
Peter Schwenke (bluetoad) wrote :

Have you got laptop mode enabled on battery? Check /etc/default/acpi-support.

That will set that parameter to an even
more aggressive value (LM_BATT_MAX_LOST_WORK_SECONDS=600 seconds in /etc/laptop-mode/laptop-mode.conf and more settings) when on battery.

Revision history for this message
Mike Fedyk (mfedyk) wrote :

I can confirm this on my laptop running gutsy. What information would you need me to provide to help find the root cause?

Revision history for this message
Peter Schwenke (bluetoad) wrote :

Ubuntu sets the values of this parameter depending if you are on AC power.

Check to make sure you have laptop mode enabled on battery power. Then run powertop wgile on battery power. You'll probably find that the message will not occur any more.

Revision history for this message
Alan Pope 🍺🐧🐱 🦄 (popey) wrote :

Yup Peter, you're right. Many thanks for clearing that up.

Revision history for this message
Alan Pope 🍺🐧🐱 🦄 (popey) wrote :

Setting to invalid as this isn't a bug.

Changed in powertop:
status: New → Invalid
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