[pkg-fso-maint] powertop - CONFIG_HPET_TIMER and CONFIG_NO_HZ

[Steffen Moeller]

Hello, I ran powertop on my Freephone and it gave me the following:

Wakeups-from-idle per second : 253.1    interval: 10.0s
no ACPI power usage estimate available

Top causes for wakeups:
  79.2% (200.4)       <interrupt> : S3C2410 Timer Tick
  12.6% ( 32.0)       <interrupt> : s3c2440-i2c
   3.2% (  8.0)              hald : schedule_timeout (process_timeout)
   2.6% (  6.6)       <interrupt> : s3c2410_udc
   0.4% (  1.1)   <kernel module> : usb_gadget_register_driver
(s3c2410_udc_vbus_poll)
   0.4% (  1.0)        frameworkd : schedule_hrtimeout_range (hrtimer_wakeup)
   0.4% (  1.0)              ntpd : hrtimer_start (it_real_fn)
   0.2% (  0.5)              hald : schedule_hrtimeout_range (hrtimer_wakeup)
   0.2% (  0.5)   <kernel module> : neigh_table_init_no_netlink
(neigh_periodic_timer)
   0.2% (  0.5)     <kernel core> : schedule_delayed_work_on
(delayed_work_timer_fn)
   0.2% (  0.4)             udevd : schedule_hrtimeout_range (hrtimer_wakeup)
   0.1% (  0.2)     <kernel core> : page_writeback_init (wb_timer_fn)
   0.1% (  0.2)      wicd-monitor : schedule_hrtimeout_range (hrtimer_wakeup)
   0.1% (  0.2)              init : schedule_hrtimeout_range (hrtimer_wakeup)
   0.0% (  0.1)     <kernel core> : neigh_add_timer (neigh_timer_handler)
   0.0% (  0.1)     <kernel core> : queue_delayed_work (delayed_work_timer_fn)
   0.0% (  0.1)     <kernel core> : neigh_table_init_no_netlink
(neigh_periodic_timer)
   0.0% (  0.1)         ssh-agent : schedule_hrtimeout_range (hrtimer_wakeup)




Suggestion: Enable the CONFIG_NO_HZ kernel configuration option.
This option is required to get any kind of longer sleep times in the CPU.

or

Suggestion: Enable the CONFIG_HPET_TIMER kernel configuration option.
Without HPET support the kernel needs to wake up every 20 milliseconds for
some housekeeping tasks.


I cannot tell if this is compatible with the remaining demands we have for the
device, but it seems like a good idea to save some battery.

Many thanks for your comments

Steffen