[Dynamicpower-devel] Re: Some DPM measures in OMAP1510

[Todd P. <tp...@mv...>]

Hello Daniel -- Thanks, I previously measured some similar OMAP1510 
Innovator configurations on an older release with similar results. 
Since the Innovator board is not intended for power consumption 
benchmarking according to the documentation from the provider, and since 
I noticed that powering up/down several onboard devices did not make a 
significant different in the amount of current drawn from the power 
supply, I didn't take it very far.  So I should note that the absolute 
values mentioned here bear little relation to power consumption to be 
expected in a real consumer electronics device based on an OMAP1510 
core, but the deltas in consumption at different power operating points 
may be instructive.

One thing I did was a find /var with NFS root:

No DPM:   906mA avg; 968mA max; 3.627sec elapsed
policy 1: 854mA avg; 910mA max; 3.766sec elapsed
policy 2: 780mA avg; 837mA max; 3.969sec elapsed

where:

No DPM = No dynamic frequency scaling, platform runs at full power 
168MHz DPLL and CPU, 84MHz Traffic Controller (TC).

policy 1 = Dynamic frequency scaling between full power (as above) when 
running tasks and 168MHz DPLL, 84MHz CPU and TC when idle.

policy 2 = No dynamic frequency scaling, platform runs at DPLL, CPU, and 
TC 60MHz.

Current measured at an idle shell prompt in those three configurations 
was 765mA, 763mA, and 713mA, respectively.  Not a large difference, 
which was in line with expectations set by the silicon vendor (basically 
WFI without other power parameter mods is about as good as you can do at 
idle for that chip).

Also measured two sleep states:

DPLL 168 MHz, CPU in Deep Sleep state, Traffic Controller left 
unchanged: 607mA

DPLL 6 MHz, CPU in Deep Sleep state, Traffic Controller 3MHz: 493mA

You mentioned your test application does not go idle, but the results 
for the 2 policies with same task cpu setting but different idle 
settings showed some difference in power consumption, perhaps it was an 
NFS root config that blocked on NFS for the app?

You also mentioned "More and different apps necessary for good DPM test" 
-- Yes, one of these days I'd like to fire up a low-bit-rate MPEG4 video 
or something that goes alternately very active and very idle and see how 
that does on various boards.

Thanks,

-- 
Todd