Thread: Overclock the N900?
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Matan is offline Matan
2010-01-27 , 13:32
Posts: 1,224 | Thanked: 1,763 times | Joined on Jul 2007
#89
Originally Posted by GeneralAntilles View Post
I'm sorry, but this opinion is just uninformed. The N900 scales the CPU clock constantly (several times a second in fact) and the built-in powersaving software will NEVER lock the CPU over 500MHz for any extended period of time. Doing is is highly likely to lead to premature failure.

This is incorrect. Nokia use standard kernel cpufreq governor (ondemand) which does no such thing. If there is constant use of cpu, it remains at maximum frequency. Maybe there is some user space program that limits maximum frequency according to some temperature sensor, but I doubt it.

See result of a very simple experiment:
Code:
N900:~# cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state ; date ; for  i in ` seq 1 10` ; do bzip2 -c9 /lib/libc-2.5.so  > /dev/null ; done ; cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state ; date
600000 20464
550000 487
500000 17132
250000 1120872
Wed Jan 27 15:24:26 IST 2010
600000 22572
550000 487
500000 17132
250000 1120875
Wed Jan 27 15:24:47 IST 2010
N900:~# date ; cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state ; for  i in ` seq 1 100` ; do bzip2 -c9 /lib/libc-2.5.so  > /dev/null ; done ; cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state ; date
Wed Jan 27 15:25:21 IST 2010
600000 22599
550000 487
500000 17132
250000 1124167
600000 43656
550000 487
500000 17132
250000 1124195
Wed Jan 27 15:28:51 IST 2010
In the first run, during 21 seconds of high cpu usage, the CPU spent 0 time at 550MHz, 0 time at 500MHz and 0.03 seconds at 250MHz.

In the second run during 210 seconds, the CPU spent 0 time at 550MHz, 0 time at 500MHz and 0.28 seconds at 250MHz.
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