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Overclocking

Revision as of 21:46, 8 April 2010

# WORK IN PROGRESS, HELP IF YOU WANT

Warnings

- Overclocking WILL VOID YOUR WARRANTY
- The lifetime of your device will get reduced
- You could lose the data in your device (file system corruption)
- Every device is an individual, what is stable for others might not be for you
- If you encounter ANY unusual problems, lower your clock frequency
- You do it at your own responsibility. No whining afterwards. If you're unsure, don't do it.

Necessary links

talk.maemo.org: Overclock the N900?

Kernels

talk.maemo.org: Compiling custom kernels for P1.1 (with fiasco-gen)

# ADD IMPORTANT POSTS FROM THE TOPICS

Useful stuff

Show current CPU frequency

awk '{print $1/1000" MHz"}' /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq

Set maximum CPU frequency

From root terminal:

echo $((600*1000)) > /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq

Replace 600 with desired maximum frequency. The list of available frequencies on your device/kernel can be obtained with command:

awk '{print $1/1000" MHz,",$2/1000" MHz,",$3/1000" MHz,",$4/1000" MHz,",$5/1000" MHz"}' /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies

If the last value returned is 0 MHz, this means that you have only 4 available frequencies.

Analyzing time_in_state

This script generates readable output (percentage) of states used. It is designed for 5 available states. If you have 4 available frequencies (stock kernel) simply remove 7th line and lower "head -n 4" to "head -n 3" in 3rd line.

#!/bin/sh
awk '{print "\nCurrent frequency: "$1/1000" MHz\n"}' /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
sum=`awk '{SUM += $2} END {print SUM}' /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state`
sum2=`cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state | head -n 4 | awk '{SUM += $2} END {print SUM}'`
cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state | head -n 1 | awk '{printf (($1/1000)" MHz: overall "); printf ("%.1f",($2 * 100)/"'"$sum"'"); printf ("'" %%, when not idle "'"); printf ("%.1f %\n",($2 * 100)/"'"$sum2"'")}'
cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state | head -n 2 | tail -n 1 | awk '{printf (($1/1000)" MHz: overall "); printf ("%.1f",($2 * 100)/"'"$sum"'"); printf ("'" %%, when not idle "'"); printf ("%.1f %\n",($2 * 100)/"'"$sum2"'")}'
cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state | head -n 3 | tail -n 1 | awk '{printf (($1/1000)" MHz: overall "); printf ("%.1f",($2 * 100)/"'"$sum"'"); printf ("'" %%, when not idle "'"); printf ("%.1f %\n",($2 * 100)/"'"$sum2"'")}'
cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state | head -n 4 | tail -n 1 | awk '{printf (($1/1000)" MHz: overall "); printf ("%.1f",($2 * 100)/"'"$sum"'"); printf ("'" %%, when not idle "'"); printf ("%.1f %\n",($2 * 100)/"'"$sum2"'")}'
cat /sys/devices/system/cpu/cpu0/cpufreq/stats/time_in_state | tail -n 1 | awk '{printf (($1/1000)" MHz: overall "); printf ("%.1f %\n\n",($2 * 100)/"'"$sum"'")}'

Output example:

Current frequency: 125 MHz

800 MHz: overall 5.0 %, when not idle 70.0 %
550 MHz: overall 0.2 %, when not idle 2.0 %
500 MHz: overall 2.0 %, when not idle 25.0 %
250 MHz: overall 0.3 %, when not idle 3.0 %
125 MHz: overall 92.5 %