How To Change The CPU Frequency?

Installation

sudo apt-get install cpufrequtils

Running

Save the below in a set_freq.sh file

sudo cpufreq-set -c0 -g userspace
sudo cpufreq-set -c1 -g userspace
sudo cpufreq-set -c2 -g userspace
sudo cpufreq-set -c3 -g userspace

sudo cpufreq-set -c0 -f $1GHz
sudo cpufreq-set -c1 -f $1GHz
sudo cpufreq-set -c2 -f $1GHz
sudo cpufreq-set -c3 -f $1GHz


cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
cat /sys/devices/system/cpu/cpu1/cpufreq/scaling_cur_freq
cat /sys/devices/system/cpu/cpu2/cpufreq/scaling_cur_freq
cat /sys/devices/system/cpu/cpu3/cpufreq/scaling_cur_freq

Now execute

chmod +x set_freq.sh

To change the frequncy exeucute the below command

./set_freq.sh 2.2

The available freqencies can be found by

more cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies

Running Benchmarks

We used Lulesh benchmark and Graph 500 for studying the change in temperature and execution time with change in frequency

Results

Frequency	Temp Core 1 ℃	Temp Core ℃	Execution Time in Seconds
1197000	35	37	79.65
2261000	39	43	40.34
2394000	39	43	39.49
2527000	41	44	37.05
2660000	43	45	35.52
2793000	43	45	34.26
2926000	43	46	33.70
3059000	44	47	32.27
3192000	45	48	30.74
3193000	45	50	31.15

Frequency vs Tempararture Graph

Frequency vs Time Graph

Temparature reading in HPC Computer

How to read CPU voltage for 64 bit computer

 sudo apt-get install msr-tools
 sudo modprobe msr
 sudo rdmsr 408 --bitfield 47:32 --decimal --processor 0

The value of register 408(x198) can be used to calculate the value of voltage. The value obtained from 32:47 bits on multiplying with (1 / 2^^13) gives the voltage.

Comparison of Frequency Vs Voltage

Max Frequency	Max Voltage	Min Voltage
1.2 GHz	0.86890 Volt	0.70386 Volt
1.4 GHz	0.86890 Volt	0.71838 Volt
1.6 GHz	0.86890 Volt	0.73291 Volt
1.8 GHz	0.86890 Volt	0.75232 Volt
2.0 GHz	0.87366 Volt	0.81055 Volt
2.2 GHz	0.87366 Volt	0.80579 Volt
2.4 GHz	0.90771 Volt	0.86890 Volt

Graph

Time for Various Programs

Program	Userspace Time	Ondemand Time
Compress 10gb file	01:55 Min	01:20 Min
Lulesh2.0	48.41 Sec	42.99 Sec
Convert File To Pdf - LibreOffice	6.41 Sec	4.30 Sec
Copy 1 GB	16.128 Sec	17.356 Sec

Comparison of Governors

The source code of Tebalo can be foun at https://github.com/CPUhackers/tebalo

Time

Program	Ondemand	Conservative	Powersave	Performance	Rounder @ 1	Rounder @ 2	Rounder @ 5
Lulesh @ 30	29.76	31.35	74.26	30.89	43.21	41.91	43.46
Lulesh @ 35	56.16	56.80	132.25	57.02	79.10	82.87	77.30
Lulesh @ 40	97.24	96.40	215.02	95.29	136.79	128.67	132.02
Lulesh @ 45	159.65	175.90	359.83	157.57	217.00	225.11	209.52

Program	Ondemand	Tebalo
Graph 0.3k 0.3k	18.52	20.24
Graph 0.5k 0.5k	27.45	28.42
Graph 0.7k 0.7k	48.52	52.24
Graph 1k 1k	84.33	88.41

Max Temparatue

Program	Ondemand	Conservative	Powersave	Performance	Rounder @ 1	Rounder @ 2	Rounder @ 5
Lulesh @ 30	58,57	56,55	44,43	56,55	55,53	56,55	55,53
Lulesh @ 35	58,56	58,56	45,44	57,56	56,55	56,55	55,53
Lulesh @ 40	60,58	60,59	45,44	59,57	57,56	58,56	57,54
Lulesh @ 45	59, 57	60,57	44,42	63,57	57,55	57,55	58,56

Min Temparatue

Program	Ondemand	Conservative	Powersave	Performance	Rounder @ 1	Rounder @ 2	Rounder @ 5
Lulesh @ 30	44,43	39,40	40,40	42,42	41, 41	41,39	39,38
Lulesh @ 35	41,40	39,39	39,39	44,42	39, 39	40,39	41,39
Lulesh @ 40	41,41	41,40	39,39	47,45	40, 40	41,40	42,40
Lulesh @ 45	37, 36	39,37	38,37	43,40	42, 40	40,39	41,39

Average Temparature

Program	Ondemand	Conservative	Powersave	Performance	Rounder @ 1	Rounder @ 2	Rounder @ 5
Lulesh @ 30	56.63,55.35	54.11, 52.81	42.53, 41.92	53.53,52.67	49.68, 48.22	49.22,47.97	49.03,46.55
Lulesh @ 35	55.32,53.96	55.01, 53.62	43.46,42.32	55.37,53.79	49.57, 48.52	50.04,48.94	48.36,46.01
Lulesh @ 40	57.01,55.38	57.09, 55.80	43.71,42.67	56.63,55.08	50.79, 49.79	51.21,50.01	50.05,47.76
Lulesh @ 45	55.51,52.91	56.34, 53.82	43.08, 40.57	56.72,53.75	50.65, 48.16	50.99,48.60	50.68,48.57