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1 2The contents of this directory allow users to specify PMU events in their3CPUs by their symbolic names rather than raw event codes (see example below).4 5The main program in this directory, is the 'jevents', which is built and6executed _BEFORE_ the perf binary itself is built.7 8The 'jevents' program tries to locate and process JSON files in the directory9tree tools/perf/pmu-events/arch/foo.10 11 - Regular files with '.json' extension in the name are assumed to be12 JSON files, each of which describes a set of PMU events.13 14 - The CSV file that maps a specific CPU to its set of PMU events is to15 be named 'mapfile.csv' (see below for mapfile format).16 17 - Directories are traversed, but all other files are ignored.18 19 - To reduce JSON event duplication per architecture, platform JSONs may20 use "ArchStdEvent" keyword to dereference an "Architecture standard21 events", defined in architecture standard JSONs.22 Architecture standard JSONs must be located in the architecture root23 folder. Matching is based on the "EventName" field.24 25The PMU events supported by a CPU model are expected to grouped into topics26such as Pipelining, Cache, Memory, Floating-point etc. All events for a topic27should be placed in a separate JSON file - where the file name identifies28the topic. Eg: "Floating-point.json".29 30All the topic JSON files for a CPU model/family should be in a separate31sub directory. Thus for the Silvermont X86 CPU:32 33 $ ls tools/perf/pmu-events/arch/x86/silvermont34 cache.json memory.json virtual-memory.json35 frontend.json pipeline.json36 37The JSONs folder for a CPU model/family may be placed in the root arch38folder, or may be placed in a vendor sub-folder under the arch folder39for instances where the arch and vendor are not the same.40 41Using the JSON files and the mapfile, 'jevents' generates the C source file,42'pmu-events.c', which encodes the two sets of tables:43 44 - Set of 'PMU events tables' for all known CPUs in the architecture,45 (one table like the following, per JSON file; table name 'pme_power8'46 is derived from JSON file name, 'power8.json').47 48 struct pmu_event pme_power8[] = {49 50 ...51 52 {53 .name = "pm_1plus_ppc_cmpl",54 .event = "event=0x100f2",55 .desc = "1 or more ppc insts finished,",56 },57 58 ...59 }60 61 - A 'mapping table' that maps each CPU of the architecture, to its62 'PMU events table'63 64 struct pmu_events_map pmu_events_map[] = {65 {66 .cpuid = "004b0000",67 .version = "1",68 .type = "core",69 .table = pme_power870 },71 ...72 73 };74 75After the 'pmu-events.c' is generated, it is compiled and the resulting76'pmu-events.o' is added to 'libperf.a' which is then used to build perf.77 78NOTES:79 1. Several CPUs can support same set of events and hence use a common80 JSON file. Hence several entries in the pmu_events_map[] could map81 to a single 'PMU events table'.82 83 2. The 'pmu-events.h' has an extern declaration for the mapping table84 and the generated 'pmu-events.c' defines this table.85 86 3. _All_ known CPU tables for architecture are included in the perf87 binary.88 89At run time, perf determines the actual CPU it is running on, finds the90matching events table and builds aliases for those events. This allows91users to specify events by their name:92 93 $ perf stat -e pm_1plus_ppc_cmpl sleep 194 95where 'pm_1plus_ppc_cmpl' is a Power8 PMU event.96 97However some errors in processing may cause the alias build to fail.98 99Mapfile format100===============101 102The mapfile enables multiple CPU models to share a single set of PMU events.103It is required even if such mapping is 1:1.104 105The mapfile.csv format is expected to be:106 107 Header line108 CPUID,Version,Dir/path/name,Type109 110where:111 112 Comma:113 is the required field delimiter (i.e other fields cannot114 have commas within them).115 116 Comments:117 Lines in which the first character is either '\n' or '#'118 are ignored.119 120 Header line121 The header line is the first line in the file, which is122 always _IGNORED_. It can be empty.123 124 CPUID:125 CPUID is an arch-specific char string, that can be used126 to identify CPU (and associate it with a set of PMU events127 it supports). Multiple CPUIDS can point to the same128 File/path/name.json.129 130 Example:131 CPUID == 'GenuineIntel-6-2E' (on x86).132 CPUID == '004b0100' (PVR value in Powerpc)133 Version:134 is the Version of the mapfile.135 136 Dir/path/name:137 is the pathname to the directory containing the CPU's JSON138 files, relative to the directory containing the mapfile.csv139 140 Type:141 indicates whether the events are "core" or "uncore" events.142 143 144 Eg:145 146 $ grep silvermont tools/perf/pmu-events/arch/x86/mapfile.csv147 GenuineIntel-6-37,v13,silvermont,core148 GenuineIntel-6-4D,v13,silvermont,core149 GenuineIntel-6-4C,v13,silvermont,core150 151 i.e the three CPU models use the JSON files (i.e PMU events) listed152 in the directory 'tools/perf/pmu-events/arch/x86/silvermont'.153