30
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 ...
27
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,...
- 1,117
26
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 ...
- 85.6k
9
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 ...
- 491
9
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 ...
- 308
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 ...
- 5,549
6
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 ...
- 2,123
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
- 6,936
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 ...
- 481
5
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%
- 51
5
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 ...
- 239
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.
...
- 7,600
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, ...
- 481k
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 ...
- 1,363
4
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: ...
- 14.9k
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 "...
- 8,096
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: ...
- 56
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, ...
- 481k
4
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 ...
- 3,968
4
votes
Accepted
Why does my CPU disregard the maximum frequency set by e.g. cpupower and how can I keep my CPU from getting too hot?
Thanks to Artem S. Tashkinov I was able to resolve the problem. He wrote in a comment
Try using acpi-cpufreq intead of intel_pstate : https://silvae86.github.io/2020/06/13/switching-to-acpi-power
...
- 71
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 ...
- 481k
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, and ...
- 114k
3
votes
Is it possible to set a *constant* lowest CPU frequency under the modern PSTATE driver?
After wasting many days in searching for a solution to set a constant frequency (to run a scientific experiment), I finally gave up. I've tried many different solutions including the performance ...
- 272
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 ...
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 ...
- 129
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 ...
- 330
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:
...
- 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/...
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 ...
- 387
3
votes
Cpu frequency is too low due to faulty battery
If manually setting values in sysfs has got no effect, this can be because the frequency is limited at bios level. If your laptop is a Thinkpad, it is certainly because the frequency is limited at ...
- 8,617
Only top scored, non community-wiki answers of a minimum length are eligible