Questions[cpufreq](ubuntu)

I mean to determine the clock speed. I am posting below the output of the various commands listed here.

For the max freq, I see 4 different sources, with 2 different values:

1. CPU max MHz: 3300,0000 from lscpu.
2. capacity: 3300MHz from lshw.
3. capacity: 3800MHz from sudo lshw.
4. Max Speed: 3800 MHz from dmidecode.

For the current freq, I see 4 different sources, with roughly 3 different values:

1. CPU MHz: 2100.000 from lscpu.
2. cpu MHz : 1691 (averaged by me) from cat /proc/cpuinfo.
3. Current Speed: 2600 MHz from dmidecode.
4. Detected 2594.332 MHz processor from cat /var/log/dmesg.

My observations:

1. There was a wide variation in the output obtained, for both the max freq and current freq. How to make sense of this? For instance, lshw gives different results with or without sudo. Is this expected? Which should be considered more reliable, and why?
2. The clock speed was even different among the 4 processors. Is such a wide variation expected?

Note: As appropriately asked by @hobbs, this OP was motivated by the need for understanding the relation between "Clock speed" (whichever variant corresponds), CPU freq spec, and memory speed spec (here there is also possibly more than one value, see e.g. dmidecode showing Memory Module Voltage: 3.3 V for DDR3 RAM).

Output:

$ lscpu | grep "MHz"
CPU MHz:                         2100.000
CPU max MHz:                     3300,0000
CPU min MHz:                     1200,0000

$ cat /proc/cpuinfo | grep "MHz"
cpu MHz         : 1753.417
cpu MHz         : 1200.000
cpu MHz         : 2212.235
cpu MHz         : 1600.000

$ lshw -c cpu | grep capacity
WARNING: you should run this program as super-user.
       capacity: 3300MHz
$ sudo lshw -c cpu | grep capacity
       capacity: 3800MHz

$ sudo dmidecode -t processor | grep "Speed"
        Max Speed: 3800 MHz
        Current Speed: 2600 MHz

$ cat /var/log/dmesg | grep "MHz processor"
[    0.000000] kernel: tsc: Detected 2594.332 MHz processor

$ cat /var/log/kern.log | grep "MHz processor"

• How can I upper limit my CPU frequency by a value?

• cpufreq offers fixing the frequency to a constant value, instead of letting it vary in a range.

• It also offers conservative, on demand, powersave, and performance. I don't know what they mean. but they don't limit the frequency either. What do the four settings mean actually? In other words, what are their policies?

I've just installed cpufreqd in a fresh installation of Ubuntu 14.04 through:

sudo apt-get install cpufreqd

After that, I tried to execute it by sudo cpufreqd. But nothing happens (neither error or indicator displayed). Even I can't see any new process in the system monitor.
Then I installed cpufrequtils through sudo apt-get install cpufrequtils and I tried again to execute sudo cpufreqd with the same (no) result.

I know there exist indicator-cpufreq, I was using it for some time; but I realized that I need something more configurable and complete like cpufreqd.

Similar alternatives to this are welcome.

The cpufreq timing statistics are all zeros:

$ sort --unique /sys/devices/system/cpu/cpu*/cpufreq/stats/time_in_state | column
1600000 0       2100000 0       2600000 0       3100000 0
1700000 0       2200000 0       2800000 0       3300000 0
1900000 0       2400000 0       2900000 0       3400000 0
2000000 0       2500000 0       3000000 0       3401000 0

How is this possible? Is there really no time spent in any state?

Details

• /proc/cpuinfo

• The CPUs are clearly transitioning between frequency states:

  $ grep --perl-regexp --only-matching '(?<=cpu MHz\t\t: )[\d.]+' /proc/cpuinfo | column
  1600.000        1600.000        3401.000        1600.000
  2900.000        1600.000        2100.000        1600.000
  $ while sleep 10; do column /sys/devices/system/cpu/cpu*/cpufreq/stats/total_trans; done
  17839   17278   17497   17336   12332   14358   14054   17647
  17885   17313   17545   17384   12359   14394   14082   17691
  17888   17323   17556   17391   12359   14399   14085   17693
  17904   17336   17576   17417   12374   14402   14091   17696
  

• Someone else asked about this on a forum but never received a reply.

I'd like to set the CPU frequency scaling governor for all cores at once instead of doing it individually for each core. Is there a way to do this?

(I know it would be easy to echo the governor to /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor, but I'm not looking for a custom solution.)