Disk is working every 3 sec only when on battery

[Milan Bouchet-Valat]

This is on Hardy from a fresh install on a Toshiba Satellite laptop.

When on AC, the disk does not work until I ask it to work, or until tracker for example starts indexing. But as soon as I unplug the cable, the disk starts working on an extremely regular way, every 3 seconds. It makes a short noise, the led shines a little, and sometimes it works again less strongly 1 sec later, sometimes twice. This never stops until I'm on AC.

atop -d reports that no process is using the disk (except for 1 sec sometimes a program coming up), but pdflush is always at the top:
  PID RDDSK WRDSK WRDSK_CANCEL DSK CMD
  157 0K 132K 0K 97% pdflush
and others are at 0% disk use.

I can find no error in my system logs. This is occurring even when I only start a standard session on a pristine user account. When only GDM is started there is an activity, but much less frequent so I think this is not the same problem.

It's just like the system has inverted its behavior and uses the disk when it shouldn't (on battery), and vice-versa!

I don't really know were I can search for more debugging nor to which package I should report it. Please just ask and I'll have a look.

[Milan Bouchet-Valat (nalimilan)]

powertop reports many things but not really what I'm looking for (since disk access is not the only power consuming work), but I can find more about pdflush there:
   0,3% ( 0,4) pdflush : do_journal_end (delayed_work_timer_fn)
Sure this is not the worse process, but this may be sufficient to prevent the hard disk from sleeping and cost more power than it appears to. So is that just a matter of filesystem journal write? I'm using reiserfs3 on my home and root partitions.

[Milan Bouchet-Valat (nalimilan)]

Here's the output of blktrace/blkparse during a "normal" period of about 5 sec, with no activity but this typical noise on my idle session.

[Federico (81joe81)]

I can confirm this behavior on my Kubuntu Hardy x86, running on an Asus laptop.
I would say that the "noise" interval in my case is even shorter, something between 1 and 2 seconds.
As already stated, the problem arises only on battery mode.

[Federico (81joe81)]

Any news about this bug?
I think it's an important issue that has started with Hardy while before it was not present.
Do you need more information? How can we provide it?

[Leann Ogasawara (leannogasawara)]

There hasn't been any recent activity in this bug report and we were wondering if this is still an issue? The Ubuntu kernel team is actively working on the upcoming Intrepid Ibex 8.10 release. If you could please test the latest Alpha release for Intrepid it would be much appreciated - http://www.ubuntu.com/testing . Please let us know your results. If the issue still exists, please also provide the appropriate debugging information as outlined at https://wiki.ubuntu.com/KernelTeamBugPolicies . Thanks in advance.

[Leann Ogasawara (leannogasawara)]

The Ubuntu Kernel Team is planning to move to the 2.6.27 kernel for the upcoming Intrepid Ibex 8.10 release. As a result, the kernel team would appreciate it if you could please test this newer 2.6.27 Ubuntu kernel. There are one of two ways you should be able to test:

1) If you are comfortable installing packages on your own, the linux-image-2.6.27-* package is currently available for you to install and test.

--or--

2) The upcoming Alpha5 for Intrepid Ibex 8.10 will contain this newer 2.6.27 Ubuntu kernel. Alpha5 is set to be released Thursday Sept 4. Please watch http://www.ubuntu.com/testing for Alpha5 to be announced. You should then be able to test via a LiveCD.

Please let us know immediately if this newer 2.6.27 kernel resolves the bug reported here or if the issue remains. More importantly, please open a new bug report for each new bug/regression introduced by the 2.6.27 kernel and tag the bug report with 'linux-2.6.27'. Also, please specifically note if the issue does or does not appear in the 2.6.26 kernel. Thanks again, we really appreicate your help and feedback.

[Milan Bouchet-Valat (nalimilan)]

It seems to have disappeared for me in Intrepid. At least I'm able to use laptop-mode, and then my disk heads can park. Can we close it or are there people still experiencing this?

[Leann Ogasawara (leannogasawara)]

Thanks Milan. Since you are the original bug reporter, lets go ahead and close this. Marking this Fix Released for Intrepid. Thanks.