diff options
Diffstat (limited to '')
| -rw-r--r-- | tools/perf/pmu-events/README | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/tools/perf/pmu-events/README b/tools/perf/pmu-events/README new file mode 100644 index 000000000..de7efa2ce --- /dev/null +++ b/tools/perf/pmu-events/README @@ -0,0 +1,152 @@ + +The contents of this directory allow 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/foo. + + - Regular files with '.json' extension in the name are assumed to be + JSON files, each of which describes a set of PMU events. + + - The CSV file that maps a specific CPU to its set of PMU events is to + be named 'mapfile.csv' (see below for mapfile format). + + - Directories are traversed, but all other files are ignored. + + - To reduce JSON event duplication per architecture, platform JSONs may + use "ArchStdEvent" keyword to dereference an "Architecture standard + events", defined in architecture standard JSONs. + Architecture standard JSONs must be located in the architecture root + folder. Matching is based on the "EventName" field. + +The PMU events supported by a CPU model are expected to grouped into topics +such as Pipelining, Cache, Memory, Floating-point etc. All events for a topic +should be placed in a separate JSON file - where the file name identifies +the topic. Eg: "Floating-point.json". + +All the topic JSON files for a CPU model/family should be in a separate +sub directory. Thus for the Silvermont X86 CPU: + + $ ls tools/perf/pmu-events/arch/x86/silvermont + cache.json memory.json virtual-memory.json + frontend.json pipeline.json + +The JSONs folder for a CPU model/family may be placed in the root arch +folder, or may be placed in a vendor sub-folder under the arch folder +for instances where the arch and vendor are not the same. + +Using the JSON files and the mapfile, 'jevents' generates the 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. + +However some errors in processing may cause the alias build to fail. + +Mapfile format +=============== + +The mapfile enables multiple CPU models to share a single set of PMU events. +It is required even if such mapping is 1:1. + +The mapfile.csv format is expected to be: + + Header line + CPUID,Version,Dir/path/name,Type + +where: + + Comma: + is the required field delimiter (i.e other fields cannot + have commas within them). + + Comments: + Lines in which the first character is either '\n' or '#' + are ignored. + + Header line + The header line is the first line in the file, which is + always _IGNORED_. It can be empty. + + CPUID: + CPUID is an arch-specific char string, that can be used + to identify CPU (and associate it with a set of PMU events + it supports). Multiple CPUIDS can point to the same + File/path/name.json. + + Example: + CPUID == 'GenuineIntel-6-2E' (on x86). + CPUID == '004b0100' (PVR value in Powerpc) + Version: + is the Version of the mapfile. + + Dir/path/name: + is the pathname to the directory containing the CPU's JSON + files, relative to the directory containing the mapfile.csv + + Type: + indicates whether the events are "core" or "uncore" events. + + + Eg: + + $ grep silvermont tools/perf/pmu-events/arch/x86/mapfile.csv + GenuineIntel-6-37,v13,silvermont,core + GenuineIntel-6-4D,v13,silvermont,core + GenuineIntel-6-4C,v13,silvermont,core + + i.e the three CPU models use the JSON files (i.e PMU events) listed + in the directory 'tools/perf/pmu-events/arch/x86/silvermont'. |