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Overclocking

Revision as of 09:12, 11 April 2010

# WORK IN PROGRESS, HELP IF YOU WANT

Overclocking is discussed in this thread. If you're more interested in power saving read this.

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.
- Nokia's overclocking warning: 500MHz is the normal frequency. Everything above is not good for your device, even with the stock kernel.

Available kernels

Overclocking requires installation of a custom kernel. There are two types of kernels:

1. modified PR1.1 kernels by Lehto and others. The only difference to the stock Nokia kernel is that the change the available hardcoded frequencies.
2. enhanced kernels by titan. They are compatible with PR1.2 (!) , contain lots of additional features (IPv6, NAT etc) and bugfixes. In addition they include a large set of possible frequencies (125MHz-1.2GHz) which you manually set an try out without flashing a new kernel. The defaults are set to the standard 250-600MHz range. The kernel can be installed via HAM from the extras-devel catalouge.

Installation of Letho's PR1.1 kernels

Lehto's Kernels talk.maemo.org: Jakiman's Overclock Guide / Summary

Installation of titan's enhanced kernels

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

latest version of the community kernel

Lower voltage versions of the same kernel

stable community kernel in extras-testing the package This version maemo19 is good for temporarily testing higher frequencies but a phone call resets the limits. It still includes the invalid 800Mhz frequency. phone call reset workaround for the older maemo19 kernel

The screen calibration in settings crashes immediately. It is a known bug in the calibration app, not in the kernel. It's mentioned in the kernel package description and is due to additional evdev (joystick,mouse) support. Just calibrate once with the stock kernel before you install the fully featured kernel.

The kernel in extras-devel is more recent.

the 125MHz issue

Installing another version of the enhanced kernel will just overwrite the older version. The stock kernel modules are preserved so that you can simply reflash the stock kernel via USB.

If you for some reason get errors like this during removal or installation

rm: cannot remove '/lib/modules/2.6.28.10maemo-lv-omap1/modules.*': No such file or directory

try this workaround There was a bug in one of the early LV kernels but it should be fixed in more recent versions.

This kernel will not conflict with the future PR1.2 upgrade. The upgrade will, however, overwrite this kernel and you'll have to install it again.

Additional information and hints

1. the frequencies available in the Nokia kernel are: 250, 500, 550 and 600MHz.
2. Nokia locks the device to 600MHz during phone calls. This may be a bug. It also affects Letho's kernels.
3. when connected via USB the device locks the minimum frequency to 500Mhz.
4. By default the device is configured to use 125MHz as the lowest frequency but it not enabled in the kernel pmconfig bug
5. improving responsiveness
6. safe pmconfig configuration
7. the warning "WARNING: at arch/arm/mach-omap2/clock34xx.c:443 omap3_noncore_dpll_set_rate+0x28c/0x2dc()" in the kernel logs (dmesg) only happens if the invalid 800MHz frequency was selected. ignore it.
8. saving more battery power when idle
9. someone has photoshopped a picture of a device being overclocked 1.7GHz. It's a FAKE!

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 %

Changing the Kernel

Installing a modified Kernel

Flashing using PC

1. Power off the N900 completely.

2. Hold "u" on the N900's keyboard, while holding, connect it to the PC via USB cable.

3. You will see usb icon on top right of white Nokia screen.

4. Now you can let go of "u" on the keyboard.

5. Now use flasher utility with the kernel file located in the same directory.

flasher-3.5 -k image_file_name -f -R

6. It should take about 1-2 seconds then it'll say Done.

7. Now your N900 will show white Nokia screen. (reboot)

8. At this time, you can pull out the USB cable.

9. N900 should finish booting up if all goes well.

10. Test out your phone as usual. (Apps, browser, camera, phone etc etc)

11. If any abnormal events occur frequently (crash, hang, screen corruption etc), turn it off, flash it to a slower kernel and test again. note: For Windows7 64bit users, you may need to use WindowsXP mode. (Youtube Tutorial)

Flashing from N900 xterminal

• do a backup, have a pc nearby and know you are able to flash the n900 with flasher-3.5 - just in case

0. Launch xterminal app then type sudo gainroot (need rootsh installed)

1. type

softupd -vv -s --local

(thats double v)

2. open new terminal

3. type

flasher --local -f -k <kernel_zimage_file_with_path>

4. you see the flashing (takes some time)

5. type "sync" to save changes

6. type "reboot" and enter to restart

7. Test out your phone as usual. (Apps, browser, camera, phone etc etc)

8. If any abnormal events occur frequently (crash, hang, screen corruption etc), turn it off, flash it to a slower kernel and test again.

You are fully responsible for any damage caused by overclocking. Not anyone else.

Reverting to the Original Kernel

If you want to revert to the original kernel, execute:

apt-get install --reinstall kernel kernel-flasher