[vdr] power consumption, powertop and wakups per second with a af9015 device

Heinrich Langos henrik-vdr at prak.org
Mon Mar 16 12:47:14 CET 2009


Hi,

I just installed vdr 1.6.0 on Debian stable (Lenny). I run it on an old 
notebook (Dell 1300, 1.5 GHz Celeron M). 
Up until now the system was a network storage for some windows clients and a 
music player for my living room. Now I plan to use vdr as a remote 
controled VCR.

To keep it quiet I checked with powertop and got rid of most software that does
short idle loops. Now the system shows less than 10 wakeups per second from
sleep. 

That is with dvb_usb_af9015 loaded but with "remote=0" module parameter 
to disable the remote control input that aparently is done by polling.
(With "remote=2" it goes up by about 50 wakeups per second. OK, AFAIK USB 
input devices need to be polled. No way around it. But does it have to be 
at 20ms intervals?)

Anyway, the real fun comes with starting vdr. With vdr runing I get a 
whopping 2700 wakeups per second! And thats doing nothing at all. No recording, 
no playback no streaming. Nada! The result is a 30% CPU load (admittetly at a 
low P-state) and a constantly runing CPU fan.

I don't know what vdr does, but it causes the device to jump through a lot of
(idle) loops. At least thats what I'd read from the output of powertop.

Does anybody have an idea as to what it causing this? 

Any comparative data for other devices? 

I also own a "Fujitsu-Siemens DVB-T Mobile TV Tuner" and I'll 
take a look and try to find out if that device will generate 
less system load.

Cheers
-henrik


Here's the idle state without vdr:
=================================
PowerTOP version 1.10      (C) 2007 Intel Corporation

Cn                Avg residency       P-states (frequencies)
C0 (cpu running)        ( 0.2%)          750 Mhz     0.0%
polling           0.0ms ( 0.0%)          563 Mhz     0.0%
C1 halt           0.0ms ( 0.0%)          375 Mhz     0.0%
C2                0.0ms ( 0.0%)          188 Mhz   100.0%
C3              102.8ms (99.8%)

Wakeups-from-idle per second :  9.7     interval: 20.0s
no ACPI power usage estimate available

Top causes for wakeups:
  38.1% (  4.9)       <interrupt> : uhci_hcd:usb3, eth0
  15.6% (  2.0)           xfsaild : schedule_timeout (process_timeout)
  13.2% (  1.7)           xfsbufd : schedule_timeout (process_timeout)
   7.8% (  1.0)          ifconfig : b44_open (b44_timer)
   5.1% (  0.7)     <kernel core> : sk_reset_timer (tcp_delack_timer)
   5.1% (  0.7)               mpd : sk_reset_timer (tcp_write_timer)
   3.9% (  0.5)     <kernel core> : schedule_delayed_work_on (delayed_work_timer_fn)
   1.9% (  0.2)   <kernel module> : neigh_table_init_no_netlink (neigh_periodic_timer)
   1.9% (  0.2)     <kernel core> : neigh_table_init_no_netlink (neigh_periodic_timer)
   1.6% (  0.2)          runsvdir : schedule_timeout (process_timeout)
   1.6% (  0.2)     <kernel core> : __netdev_watchdog_up (dev_watchdog)
   1.6% (  0.2)              init : schedule_timeout (process_timeout)
   0.8% (  0.1)            screen : do_setitimer (it_real_fn)
   0.8% (  0.1)              nmbd : schedule_timeout (process_timeout)
   0.4% (  0.1)     <kernel core> : neigh_add_timer (neigh_timer_handler)
   0.4% (  0.1)     <kernel core> : queue_delayed_work (delayed_work_timer_fn)
   0.4% (  0.1)          xfssyncd : schedule_timeout (process_timeout)

=================================

and here's the "idle" state with vdr:

=================================
     PowerTOP version 1.10      (C) 2007 Intel Corporation

Cn                Avg residency       P-states (frequencies)
C0 (cpu running)        (29.4%)          750 Mhz     0.0%
polling           0.0ms ( 0.0%)          563 Mhz     0.0%
C1 halt           0.0ms ( 0.0%)          375 Mhz     0.0%
C2                0.0ms ( 0.0%)          188 Mhz   100.0%
C3                0.2ms (70.5%)

Wakeups-from-idle per second : 2878.8   interval: 10.0s
no ACPI power usage estimate available

Top causes for wakeups:
  60.2% (4431.3)   USB device  5-1 : DVB-T 2 (Afatech)
  39.4% (2897.7)       <interrupt> : uhci_hcd:usb1, ehci_hcd:usb5, HDA Intel
   0.1% (  7.7)             klogd : ehci_work (ehci_watchdog)
   0.1% (  5.1)           vdr-kbd : schedule_timeout (process_timeout)
   0.1% (  4.4)       <interrupt> : uhci_hcd:usb3, eth0
   0.1% (  3.7)           vdr-kbd : futex_wait (hrtimer_wakeup)
   0.0% (  2.0)           xfsaild : schedule_timeout (process_timeout)
   0.0% (  1.6)           xfsbufd : schedule_timeout (process_timeout)
   0.0% (  1.0)          ifconfig : b44_open (b44_timer)
   0.0% (  0.9)    kdvb-ad-0-fe-0 : schedule_timeout (process_timeout)
   0.0% (  0.6)     <kernel core> : sk_reset_timer (tcp_delack_timer)
   0.0% (  0.6)               mpd : sk_reset_timer (tcp_write_timer)
   0.0% (  0.5)     <kernel core> : schedule_delayed_work_on (delayed_work_timer_fn)
   0.0% (  0.3)   <kernel module> : neigh_table_init_no_netlink (neigh_periodic_timer)
   0.0% (  0.2)     <kernel core> : __netdev_watchdog_up (dev_watchdog)
   0.0% (  0.2)          xfssyncd : schedule_timeout (process_timeout)
   0.0% (  0.2)          runsvdir : schedule_timeout (process_timeout)
   0.0% (  0.2)     <kernel core> : neigh_table_init_no_netlink (neigh_periodic_timer)
   0.0% (  0.2)              init : schedule_timeout (process_timeout)
   0.0% (  0.1)           syslogd : do_setitimer (it_real_fn)
   0.0% (  0.1)              nmbd : schedule_timeout (process_timeout)

=================================




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