[Pkg-utopia-maintainers] Bug#689298: upowerd goes crazy w/o /proc/timer_stats

[Jamie Heilman]

OK, I'm able to confirm the CPU waste on a kernel built without
CONFIG_TIMER_STATS=y run under qemu-kvm.  I still haven't made upowerd
leak memory like I saw in the wild yet though.

To reproduce:

    build and run a kernel without CONFIG_TIMER_STATS=y 
    run gnome-power-statistics

after some seconds you'll observe both gnome-power-statistics and
upowerd using gobs of CPU without actually getting anything done.
In my qemu-kvm testbed, gnome-power-statistics becomes completely
unresponsive and I have to send it SIGTERM to kill it.  The upowerd
CPU consumption continues even after gnome-power-statistics is dead
and gone though.  Eventually dbus-daemon is seen to grow in both CPU
utilization (though not to the grand scope of upowerd) and noticably
in resident memory as well.  In short, a kernel built without the
debugging interface for timer statistics will cause a chain reaction
of instability and farcical resource consumption.

strace of upowerd shows runaway attempts to open the non-existant
/proc/timer_stats and subsequent logging of the failure, while it
streams a continual raft of ultimately useless messages to the dbus
machinery.

-- 
Jamie Heilman                     http://audible.transient.net/~jamie/