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28 votes

Why are my benchmark times not repeatable, even for a CPU-bound task?

TL, DR: sudo cpupower -c 0 frequency-set -g performance taskset -c 0 ./my-benchmark … sudo cpupower -c 0 frequency-set -g powersave Explanation What's going on is that the processor in a modern ...
Gilles 'SO- stop being evil''s user avatar
26 votes

Is it possible to set a *constant* lowest CPU frequency under the modern PSTATE driver?

Well, well, turns out that the new pstate Intel driver is awesome, but first one needs to practice a bit of the ancient, lost art of reading the documentation. I'll leave my question as it is because,...
Mephisto's user avatar
  • 1,087
24 votes

What are the implications of setting the CPU governor to "performance"?

For the record, the (up-to-date) cpufreq documentation is here. What does "statically" mean?To me, it contrasts with "dynamic", and implies frequency would never change, i.e. with powersave the ...
don_crissti's user avatar
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8 votes
Accepted

CPU temperatures in linux: throttling or wrong reading?

The difference is due to windows and linux using different CPU throttling profiles. You do have some control over this on linux. For example, the following command will show you which profile is ...
Jeff A's user avatar
  • 481
7 votes
Accepted

Turn off CPU turbo-boost for a process

That's what cpulimit is for: cpulimit --exe=gzip --background --limit=100 cpulimit --exe=tar --background --limit=100 this will limit the total CPU usage of the most CPU-resource intensive programs ...
Fabby's user avatar
  • 5,394
7 votes
Accepted

Set CPU to high performance

The solution turned out to be to pass intel_pstate=passive to kernel. Then intel_pstate relinquishes control back to CPUFreq. The latter still uses intel_pstate to govern the CPU, but intel_pstate has ...
facetus's user avatar
  • 268
5 votes

What are the frequencies displayed in /proc/cpuinfo?

This is the frequency of your cores, and you have cores which run with the minimum frequency, and other more stressed which run with higher frequency. You can have more information and explanation ...
Hamza Jabbour's user avatar
5 votes

Turn off CPU turbo-boost for a process

/usr/local/bin/myproclimitator: #!/bin/bash # PIDNUM=$1 while sleep 1;do kill -CONT $PIDNUM sleep 0.1 kill -STOP $PIDNUM || exit done Call it like: myproclimitator pidnum
Luciano Andress Martini's user avatar
5 votes
Accepted

System Clock vs. Hardware Clock (RTC) in embedded systems

both clock run at same frequency? Usually there are two clocks inside a computer/device/system. One is powered from a battery (usually a CR2032, could be the main battery or even a supercap in an ...
QuartzCristal's user avatar
4 votes

how to turbo boost my cpu on Ubuntu?

You don't have to do anything; the CPU will do it all by itself in when useful and possible. See Intel Turbo Boost Technology 2.0. Essentially Turbo Boost will temporarily increase the speed of a ...
AlexP's user avatar
  • 10.5k
4 votes

How to force all CPU cores to run at maximum turbo boost frequency?

In short, no, it's not possible. As you can see from the output of cpupower, your CPU only supports a maximum of 3,600Mhz with 4 cores active. When it's running at 3,900Mhz only 1 core is active. ...
mjturner's user avatar
  • 7,370
4 votes

Get all available frequency steps

I've searched around and as comments say there doesn't appear to be a table of frequencies maintained anymore. Assuming the frequencies are scaled linearly you can approximate them by looking at the ...
WinEunuuchs2Unix's user avatar
4 votes
Accepted

What is CPU min MHz in lscpu output?

It’s the slowest speed at which the processor can run, e.g. if the CPU doesn’t have much to do (depending on the governor in use) but can’t go to sleep, or if it’s throttled (from overheating, ...
Stephen Kitt's user avatar
4 votes
Accepted

Linux utility to bench mark clock speed of CPU

Use the command: lscpu To know all your CPU Specs: To get the specific frequency of your CPU use the command with a grep like so: lscpu | grep MHz It will give you output like: CPU MHz: ...
Gene Yuss's user avatar
4 votes

Turn off CPU turbo-boost for a process

From Processor boosting control: /sys/devices/system/cpu/cpufreq/boost controls the boost setting for the whole system. You can read and write that file with either "0" (boosting disabled) or ...
JigglyNaga's user avatar
  • 7,906
4 votes
Accepted

How can my cpu frequency be above maximum MHz value in lscpu?

In both cases, your CPU can run slightly faster than its specified frequency, typically when one of its cores is running a CPU-intensive process, and the others aren’t. On your Core 2 Mobile system, ...
Stephen Kitt's user avatar
4 votes

Why are my benchmark times not repeatable, even for a CPU-bound task?

In addition to Gilles' answer, contemporary CPUs are very complex, with branch predictors, readahead units, multiple levels of cache, and multiple cores that interact with each other and need to share ...
G. Sliepen's user avatar
3 votes
Accepted

Set critical CPU temperature for thermal throttling

There is a hack solution via shellscript: https://github.com/Sepero/temp-throttle/ #!/bin/bash # Usage: temp_throttle.sh max_temp # USE CELSIUS TEMPERATURES. # version 2.20 cat << EOF Author: ...
Ipor Sircer's user avatar
  • 14.6k
3 votes

/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed: Invalid argument

The files in sysfs and procfs are interfaces to the kernel. Reading and writing to these files invokes code in a driver in the kernel. If you get the error “permission denied” (EACCESS), that comes ...
Gilles 'SO- stop being evil''s user avatar
3 votes
Accepted

What is the unit of this value

The values are given in kHz (see the documentation). So 60000 is 60 MHz, 396000 is 396 MHz.
Stephen Kitt's user avatar
3 votes

Limit CPU frequency/usage energy-management style

You could set your CPU scaling govenor to powersave See link Which runs the CPU at the minimum frequency. According to the same wiki page you need to load the right cpu frequency driver ie. speedstep-...
Michael D.'s user avatar
  • 2,880
3 votes

Why is /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed not modifiable by sudo emacs?

From the comments: When Emacs saves a file, it renames the old file so that it becomes a backup file, and then creates a new file with the original name. I don't know what happened in your case, ...
telcoM's user avatar
  • 99.3k
3 votes

Is it possible to set a *constant* lowest CPU frequency under the modern PSTATE driver?

It works for me with: echo "50" | sudo tee /sys/devices/system/cpu/intel_pstate/max_perf_pct it run only 50% performance/speed while CPU load is 100%
Taufik's user avatar
  • 31
3 votes

Change the cpufreq driver from intel pstate to acpi

intel_pstate manages compatible CPUs in a more fine-grained manner than the ACPI driver can, so in general you’re better off letting it handle things. With recent kernels, it is possible to disable ...
Stephen Kitt's user avatar
3 votes

CPU temperatures in linux: throttling or wrong reading?

I believe the reason for the difference is because your Windows installation has the Intel Dynamic Platform and Thermal Framework driver which adjusts the frequencies to manage the temperature. Your ...
Lamp's user avatar
  • 131
3 votes
Accepted

How to manually set CPU clock frequency in Fedora?

Use the command cpupower --cpu all frequency-info | grep "current CPU" to see what the frequency the cores are running at. Use the command cpupower --cpu all frequency-set --max 1.4GHz to set the ...
David's user avatar
  • 280
3 votes
Accepted

Horrible performance on battery with intel_pstate driver

The issue was the intel_pstate driver. I switched to the original ACPI driver via boot kernel parameters. Specifically, in /etc/default/grub, I changed the DEFAULT boot line to: ...
rveale's user avatar
  • 161
3 votes

How can I get the current CPU frequency of an ARM processor on Ubuntu?

on a pi 4 with a recent kernel /sys/devices/system/cpu/cpufreq/ and it's children are present if you are lucky , your platform provides something like: /sys/devices/platform/soc/soc:firmware/...
Benji over_9000 'benchonaut''s user avatar
3 votes

Stop specific processes from heating up my system's CPU

I found out that some governors (ondemand and conservative) support a flag to ignore processes with a positive nice value when choosing to scale up or down. From the kernel.org CPUFreq Governors ...
peoro's user avatar
  • 3,818
3 votes

CPU Frequency drops under load without thermal issues

Probably your embedded controller is set to a conservative thermal setting. Note that these settings are persistent on the mainboard and not the hard disk. So if you are playing with Lenovos tools ...
Marc Wittke's user avatar

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