2 The contents of this directory allow users to specify PMU events in their
3 CPUs by their symbolic names rather than raw event codes (see example below).
5 The main program in this directory, is the 'jevents', which is built and
6 executed _BEFORE_ the perf binary itself is built.
8 The 'jevents' program tries to locate and process JSON files in the directory
9 tree tools/perf/pmu-events/arch/foo.
11 - Regular files with '.json' extension in the name are assumed to be
12 JSON files, each of which describes a set of PMU events.
14 - The CSV file that maps a specific CPU to its set of PMU events is to
15 be named 'mapfile.csv' (see below for mapfile format).
17 - Directories are traversed, but all other files are ignored.
19 The PMU events supported by a CPU model are expected to grouped into topics
20 such as Pipelining, Cache, Memory, Floating-point etc. All events for a topic
21 should be placed in a separate JSON file - where the file name identifies
22 the topic. Eg: "Floating-point.json".
24 All the topic JSON files for a CPU model/family should be in a separate
25 sub directory. Thus for the Silvermont X86 CPU:
27 $ ls tools/perf/pmu-events/arch/x86/Silvermont_core
28 Cache.json Memory.json Virtual-Memory.json
29 Frontend.json Pipeline.json
31 The JSONs folder for a CPU model/family may be placed in the root arch
32 folder, or may be placed in a vendor sub-folder under the arch folder
33 for instances where the arch and vendor are not the same.
35 Using the JSON files and the mapfile, 'jevents' generates the C source file,
36 'pmu-events.c', which encodes the two sets of tables:
38 - Set of 'PMU events tables' for all known CPUs in the architecture,
39 (one table like the following, per JSON file; table name 'pme_power8'
40 is derived from JSON file name, 'power8.json').
42 struct pmu_event pme_power8[] = {
47 .name = "pm_1plus_ppc_cmpl",
48 .event = "event=0x100f2",
49 .desc = "1 or more ppc insts finished,",
55 - A 'mapping table' that maps each CPU of the architecture, to its
58 struct pmu_events_map pmu_events_map[] = {
69 After the 'pmu-events.c' is generated, it is compiled and the resulting
70 'pmu-events.o' is added to 'libperf.a' which is then used to build perf.
73 1. Several CPUs can support same set of events and hence use a common
74 JSON file. Hence several entries in the pmu_events_map[] could map
75 to a single 'PMU events table'.
77 2. The 'pmu-events.h' has an extern declaration for the mapping table
78 and the generated 'pmu-events.c' defines this table.
80 3. _All_ known CPU tables for architecture are included in the perf
83 At run time, perf determines the actual CPU it is running on, finds the
84 matching events table and builds aliases for those events. This allows
85 users to specify events by their name:
87 $ perf stat -e pm_1plus_ppc_cmpl sleep 1
89 where 'pm_1plus_ppc_cmpl' is a Power8 PMU event.
91 However some errors in processing may cause the perf build to fail.
96 The mapfile enables multiple CPU models to share a single set of PMU events.
97 It is required even if such mapping is 1:1.
99 The mapfile.csv format is expected to be:
102 CPUID,Version,Dir/path/name,Type
107 is the required field delimiter (i.e other fields cannot
108 have commas within them).
111 Lines in which the first character is either '\n' or '#'
115 The header line is the first line in the file, which is
116 always _IGNORED_. It can empty.
119 CPUID is an arch-specific char string, that can be used
120 to identify CPU (and associate it with a set of PMU events
121 it supports). Multiple CPUIDS can point to the same
125 CPUID == 'GenuineIntel-6-2E' (on x86).
126 CPUID == '004b0100' (PVR value in Powerpc)
128 is the Version of the mapfile.
131 is the pathname to the directory containing the CPU's JSON
132 files, relative to the directory containing the mapfile.csv
135 indicates whether the events or "core" or "uncore" events.
140 $ grep Silvermont tools/perf/pmu-events/arch/x86/mapfile.csv
141 GenuineIntel-6-37,V13,Silvermont_core,core
142 GenuineIntel-6-4D,V13,Silvermont_core,core
143 GenuineIntel-6-4C,V13,Silvermont_core,core
145 i.e the three CPU models use the JSON files (i.e PMU events) listed
146 in the directory 'tools/perf/pmu-events/arch/x86/Silvermont_core'.