Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com> --- tools/perf/pmu-events/README | 115 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 tools/perf/pmu-events/README
diff --git a/tools/perf/pmu-events/README b/tools/perf/pmu-events/README new file mode 100644 index 0000000..00fd2e1 --- /dev/null +++ b/tools/perf/pmu-events/README @@ -0,0 +1,115 @@ +The contents of this directory allows users to specify PMU events in +their CPUs by their symbolic names rather than raw event codes (see +example below). + +The main program in this directory, is the 'jevents', which is built and +executed _before_ the perf binary itself is built. + +The 'jevents' program tries to locate and process JSON files in the directory +tree tools/perf/pmu-events/arch/xxx. + + - Regular files with '.json' extension in the name are assumed to be + JSON files. + + - Regular files with base name starting with 'mapfile.csv' are assumed + to be a CSV file that - maps a specific CPU to its set of PMU events. + +Directories are traversed, but all other files are ignored. + +Using the JSON files and the mapfile, 'jevents' generates a C source file, +'pmu-events.c', which encodes the two sets of tables: + + - Set of 'PMU events tables' for all known CPUs in the architecture, + (one table like the following, per JSON file; table name 'pme_power8' + is derived from JSON file name, 'power8.json'). + + struct pmu_event pme_power8[] = { + + ... + + { + .name = "pm_1plus_ppc_cmpl", + .event = "event=0x100f2", + .desc = "1 or more ppc insts finished,", + }, + + ... + } + + - A 'mapping table' that maps each CPU of the architecture, to its + 'PMU events table' + + struct pmu_events_map pmu_events_map[] = { + { + .cpuid = "004b0000", + .version = "1", + .type = "core", + .table = pme_power8 + }, + { + ... + }, + + }; + +After the 'pmu-events.c' is generated, it is compiled and the resulting +'pmu-events.o' is added to 'libperf.a' which is then used to build perf. + +NOTES: + 1. Several CPUs can support same set of events and hence use a common + JSON file. Hence several entries in the pmu_events_map[] could map + to a single 'PMU events table'. + + 2. The 'pmu-events.h' has an extern declaration for the mapping table + and the generated 'pmu-events.c' defines this table. + + 3. _All_ known CPU tables for architecture are included in the perf + binary. + +At run time, perf determines the actual CPU it is running on, finds the +matching events table and builds aliases for those events. This allows +users to specify events by their name: + + $ perf stat -e pm_1plus_ppc_cmpl sleep 1 + +where 'pm_1plus_ppc_cmpl' is a Power8 PMU event. + +In case of errors when processing files in the tools/perf/pmu-events/arch +directory, 'jevents' tries to create an empty mapping file to allow perf +build to succeed even if the PMU event aliases cannot be used. + +However some errors in processing may cause the perf build to fail. + +The mapfile format is expected to be: + + Header line + CPUID,Version,JSON/file/path/name,Type + +where: + + Lines in which the first character is either '\n' or '#' are ignored. + + Header line + is the first line in the file and is ignored. Even if + first line is empty or is a comment, subsequent non-comment/ + blank lines are expected to adhere to the format of the second + line above. + + Comma: + is the required field delimiter (i.e other fields cannot + have commas within them) + + CPUID: + represents is an arch-specific CPUID for the set of CPUs + that use the PMU events specified in JSON/file/path/name. + (Multiple CPU ids can point to the same JSON/file/path/name) + + Version: + is the Version of the mapfile. + + JSON/file/path/name: + is the pathname for the JSON file, relative to the directory + containing the mapfile.csv + + Type: + indicates whether the events or "core" or "uncore" events. -- 1.7.9.5 _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev