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C bindings to CPUFreq in Linux sysfs
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powercap/cpufreq-bindings
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The projects provides thecpufreq-bindings C library.
For Linux kernel documentation on cpufreq, see:https://www.kernel.org/doc/Documentation/cpu-freq/user-guide.txt
If using this project for other scientific works or publications, please reference:
- Connor Imes, Huazhe Zhang, Kevin Zhao, Henry Hoffmann. "CoPPer: Soft Real-time Application Performance Using Hardware Power Capping". In: IEEE International Conference on Autonomic Computing (ICAC). 2019. DOI:https://doi.org/10.1109/ICAC.2019.00015
This project uses CMake.
To build, run:
mkdir _buildcd _buildcmake ..makeTo install, run with proper privileges:
make install
On Linux, installation typically places libraries in/usr/local/lib and header files in/usr/local/include.
Install must be run before uninstalling in order to have a manifest.To uninstall, run with proper privileges:
make uninstall
Get linker information withpkg-config:
pkg-config --libs cpufreq-bindings
Or in your Makefile, add to your linker flags with:
$(shell pkg-config --libs cpufreq-bindings)
Depending on your install location, you may also need to augment your compiler flags with:
pkg-config --cflags cpufreq-bindings
See theinc/cpufreq-bindings.h header file for function descriptions.
A simple example of setting DVFS frequencies (error checking is ignored):
// In real scenarios, core count and IDs could be discovered dynamically using other meansuint32_tNCORES=4;uint32_tCORE_IDS[]= {0,1,2,3 };uint32_tavailable_freqs[32];intsetspeed_fds[NCORES];uint32_ti,j,nfreqs,freq;// populate "available_freqs" arraynfreqs=cpufreq_bindings_get_scaling_available_frequencies(-1,CORE_IDS[0],available_freqs,32);for (i=0;i<NCORES;i++) {// set "userspace" governor on all corescpufreq_bindings_set_scaling_governor(-1,CORE_IDS[i],"userspace",sizeof("userspace"));// cache file descriptors for setting frequencies with "userspace" governor// a "performance" governor would instead use CPUFREQ_BINDINGS_FILE_SCALING_MAX_FREQsetspeed_fds[i]=cpufreq_bindings_file_open(CORE_IDS[i],CPUFREQ_BINDINGS_FILE_SCALING_SETSPEED,-1); }// do application work, breaking from loop when finished...while (do_work()) {// pick new frequency from "available_freqs" for 0 <= j < nfreqsfreq=available_freqs[j];for (i=0;i<NCORES;i++) {// set new frequencies using cached file descriptorscpufreq_bindings_set_scaling_setspeed(setspeed_fds[i],CORE_IDS[i],freq); } }for (i=0;i<NCORES;i++) {// close cached file descriptorscpufreq_bindings_file_close(setspeed_fds[i]);// perhaps set scaling governor back to "ondemand", or whatever the system default iscpufreq_bindings_set_scaling_governor(-1,CORE_IDS[i],"ondemand",sizeof("ondemand")); }
Find this and related project sources at thepowercap organization on GitHub.
This project originates at:https://github.com/powercap/cpufreq-bindings
Bug reports and pull requests are welcome.
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C bindings to CPUFreq in Linux sysfs