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Updated Build (markdown) authored by Thomas Gruber's avatar Thomas Gruber
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......@@ -58,7 +58,7 @@ Per default the LIKWID library is build as a shared library. You need the librar
LIKWID can be built to run on top of `perf_event` (`config.mk`: `USE_PERF_EVENT` in 4.2 and `ACCESSMODE=perf_event` in 4.3), an interface of the Linux kernel to the hardware performance monitors. The events and counters are the same but not all might be supported. LIKWID supports the Uncore and RAPL (energy) units provided by perf. The thermal module is currently not supported with perf_event as perf_event does not provide thermal information.
For core-local measurements the paranoid level of 1 is enough to measure applications. To get the same behavior as native access, the paranoid level must be 0 or less. 0 or less is also required for Uncore measurements.
Be aware that LIKWID reads information out of registers that is not provided by any other source like procfs and sysfs. When switching to perf_event backend, these registers cannot be accessed and less information is printed. An example for this are the different CPU core frequencies in turbo mode (`likwid-powermeter -i`). If you want to use perf_event for measurements and the access daemon for other operations, install LIKWID first with `ACCESSMODE=accessdaemon` and followed by `make distclean`, change `ACCESSMODE=perf_event` in `config.mk` and then build and install LIKWID again.
Be aware that LIKWID reads information out of registers that is not provided by any other source like procfs and sysfs. When switching to perf_event backend, these registers cannot be accessed and less information is printed. The different CPU core frequencies in turbo mode (`likwid-powermeter -i`) serve as an example. If you want to use perf_event for measurements and the access daemon for other operations, install LIKWID first with `ACCESSMODE=accessdaemon` and followed by `make distclean`, change `ACCESSMODE=perf_event` in `config.mk` and then build and install LIKWID again.
If you have no root permissions for `make install`, please set `BUILDFREQ=false` in config.mk. The build of the access daemon is disabled when `ACCESSMODE=perf_event`. If you encounter problems, you can manually disable it by setting `BUILDDAEMON=false` in config.mk
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