xfsaild causing 30+ wakeups/s on an idle system since 2.6.25-rcX

[Török Edwin]

Hi,

xfsaild is causing many wakeups, a quick investigation shows
xfsaild_push is always
returning 30 msecs timeout value.

This is on an idle system, running only gnome, and gnome-terminal.

I suggest changing the timeout logic in xfsaild to be more power
consumption friendly.

See below my original report to the powerTOP mailing list.

Best regards,
--Edwin
> --- Begin Message ---
> Török Edwin wrote:
> > Török Edwin wrote:
> > > Hi,
> > >
> > > On latest -git of 2.6.25 I am getting lots of wakeups from xfsaild.
> > >   23.5% ( 33.3)           xfsaild : schedule_timeout (process_timeout)
> > >   
> >
> > [Should I Cc: xfs mailing list / lkml on this?]
> >
> > The problem seems to be with the timeout logic in xfsaild_push, which
> > can return 3 timeout values (msecs): 1000, 10, 20, 30.
> > I inserted a marker and attached a probe function, schedule_timeout
> > always got called with 9 jiffies (which is 30 msecs, I have HZ=300).
> >
> > Changing xfs_trans_ail.c:270 from "tout += 20" to "tout = 1000", made
> > xfsaild only do 1 wakeup/s instead of 33!
> >
> > For some reason xfs_aild always thinks it has work (I/O) to do, and
> > never chooses the 1000 msec sleep value.
>
> sounds like an XFS bug... worth reporting to the xfs/lkml folks for sure.
>
>
> --- End Message ---