Why is the e500v2 core not using cpuidle?

Thomas Waldecker Thomas.Waldecker at tqs.de
Thu Feb 7 23:19:25 EST 2013


Hi Scott,

I measured the power consumption of the whole system on the tqmp2020 ( http://tq-group.com/tqmp2020 )
with a QorIQ P2020.

Kernel:
root at generic-powerpc-e500v2:/sys/power# uname -a
Linux generic-powerpc-e500v2 3.7.0-rc8-00004-g6e93414 #4 SMP Tue Dec 11 08:53:23 CET 2012 ppc GNU/Linux
root at generic-powerpc-e500v2:/sys/power# cat /etc/issue
ELDK 5.2.1 \n \l

In idle using doze I got:
545mA, 18V => 9.81W

In idle using nap I got:
500mA, 18V => 9W

That's a difference of 0.81W,
0.81W/9.81W = 0.083 (8.3 %)

> The only way you'll get into sleep mode is through /sys/power/state.

How can I use this interface?

root at generic-powerpc-e500v2:/sys/power# ls -la
total 0
drwxr-xr-x  2 root root    0 Feb  1 15:39 .
dr-xr-xr-x 12 root root    0 Feb  1 15:19 ..
-rw-r--r--  1 root root 4096 Feb  1 15:39 state
root at generic-powerpc-e500v2:/sys/power# cat state
root at generic-powerpc-e500v2:/sys/power# echo "sleep" > state
-sh: echo: write error: Function not implemented
root at generic-powerpc-e500v2:/sys/power# echo 0 > state
-sh: echo: write error: Function not implemented
root at generic-powerpc-e500v2:/sys/power#

Kind regards
Thomas Waldecker


More information about the Linuxppc-dev mailing list