Use cpulimit to free up your CPU

stay Linux The recommended tool for managing system resources on the system is  cgroups. Although in terms of adjustable restrictions （CPU、 Memory 、 disk I/O、 Network, etc ） Very powerful , But configuration cgroups Not simple .nice  Command from the 1973 It can be used since . But it just adjusts the scheduling priority between processes competing for time on a processor .nice  The command does not limit what a process can consume per unit time CPU Percentage of period .cpulimit  The command provides the best solution for both worlds . It limits the amount of time a process can allocate per unit of time CPU Percentage of period , And relatively easy to call .

cpulimit  The command is mainly for long-running and CPU Intensive processes are useful . Compiling software and converting video are common examples of long-running processes , They can make the computer CPU Maximum utilization . Limit the of such processes CPU Utilization will free up processor time , For other tasks that may run on your computer . Limit CPU Intensive processes will also reduce power consumption and heat output , And may reduce the fan noise of the system . Limit the of a process CPU The cost of utilization is , It takes more time to finish running .

install cpulimit

cpulimit  The command is in the default Fedora Linux Available in the warehouse . Run the following command , stay Fedora Linux Installation on system  cpulimit：

$ sudo dnf install cpulimit

see cpulimit Documents

cpulimit  There are no man pages attached to the package . Use the following command to view  cpulimit  Built in documentation . The output is provided below . But you may need to run this command on your own system , To prevent options from changing since this article was written .

$ cpulimit --helpUsage: cpulimit [OPTIONS…] TARGET   OPTIONS      -l, --limit=N percentage of cpu allowed from 0 to 800 (required)      -v, --verbose show control statistics      -z, --lazy exit if there is no target process, or if it dies      -i, --include-children limit also the children processes      -h, --help display this help and exit   TARGET must be exactly one of these:      -p, --pid=N pid of the process (implies -z)      -e, --exe=FILE name of the executable program file or path name      COMMAND [ARGS] run this command and limit it (implies -z)

demonstration

To demonstrate  cpulimit  How to use the command , Here is a well-designed 、 A lot of calculation Python Script . The script first runs without restrictions , Then limit to 50% Operation in case of . It calculates the number 42 individual   Fibonacci number   Value . In both cases, the script acts as  time  The subprocess of the command runs , To display the total time required to calculate the answer .

$ /bin/time -f '(computed in %e seconds)' /bin/python -c 'f = lambda n: n if n<2 else f(n-1)+f(n-2); print(f(42), end=" ")'267914296 (computed in 51.80 seconds)$ /bin/cpulimit -i -l 50 /bin/time -f '(computed in %e seconds)' /bin/python -c 'f = lambda n: n if n<2 else f(n-1)+f(n-2); print(f(42), end=" ")'267914296 (computed in 127.38 seconds)

When running the first version of the command , You may hear on the computer CPU The fan turns . But when running the second version , You should not . The first version of the command is not affected by CPU The limitation of , But it should not paralyze your computer . It is written in such a way ： It can only use at most one CPU The core . Most modern PC There are many CPU The core , When one of them CPU 100% When busy , You can run other tasks at the same time without difficulty . To verify that the first command maximizes one of your processors , Run in a separate terminal window  top  Command and press  1  key . To exit  top  You can press the command  Q  key .

Set higher than 100% The limit is only to be able to   Task parallelization   Your program makes sense . For such a program , higher than 100% The increment of represents a CPU Total utilization of （200%=2 individual CPU,300%=3 individual CPU, wait ）.

Be careful , In the example above ,-i  Options have been passed to  cpulimit  command . This is necessary , Because the command to limit is not  cpulimit  Direct subprocess of the command . contrary , It is  time  A subprocess of the command , The latter is  cpulimit  A subprocess of the command . without  -i  Options ,cpulimit  Will only limit  time  command .

The last show

If you want to limit a graphics program that starts from a desktop icon , Please send... Of the program  .desktop  file （ Usually located in  /usr/share/applications  Under the table of contents ） Copy to your  ~/.local/share/applications  Under the table of contents , And modify it accordingly  Exec  That's ok . Then run the following command to apply these changes ：

$ update-desktop-database ~/.local/share/applications