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![John Garry](/assets/img/avatar_default.png)
For some architectures (like arm), there are architecture- defined events. Sometimes these events may be "recommended" according to the architecture standard, in that the implementer is free ignore the "recommendation" and create its custom event. This patch adds support for parsing standard events from arch-defined JSONs, and fixing up vendor events when they have implemented these events as standard. Support is also ensured that the vendor may implement their own custom events. A new step is added to the pmu events parsing to fix up the vendor events with the arch-standard events. The arch-defined JSONs must be placed in the arch root folder for preprocessing prior to tree JSON processing. In the vendor JSON, to specify that the arch event is supported, the keyword "ArchStdEvent" should be used, like this: [ { "ArchStdEvent": "L1D_CACHE_WR", }, ] Matching is based on the "EventName" field in the architecture JSON. No other JSON objects are strictly required. However, for other objects added, these take precedence over architecture defined standard events, thus supporting separate events which have the same event code. Signed-off-by: John Garry <john.garry@huawei.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Shaokun Zhang <zhangshaokun@hisilicon.com> Cc: Will Deacon <will.deacon@arm.com> Cc: William Cohen <wcohen@redhat.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linuxarm@huawei.com Link: http://lkml.kernel.org/r/1520506716-197429-8-git-send-email-john.garry@huawei.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
152 lines
4.7 KiB
Text
152 lines
4.7 KiB
Text
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The contents of this directory allow users to specify PMU events in their
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CPUs by their symbolic names rather than raw event codes (see example below).
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The main program in this directory, is the 'jevents', which is built and
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executed _BEFORE_ the perf binary itself is built.
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The 'jevents' program tries to locate and process JSON files in the directory
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tree tools/perf/pmu-events/arch/foo.
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- Regular files with '.json' extension in the name are assumed to be
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JSON files, each of which describes a set of PMU events.
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- The CSV file that maps a specific CPU to its set of PMU events is to
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be named 'mapfile.csv' (see below for mapfile format).
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- Directories are traversed, but all other files are ignored.
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- To reduce JSON event duplication per architecture, platform JSONs may
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use "ArchStdEvent" keyword to dereference an "Architecture standard
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events", defined in architecture standard JSONs.
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Architecture standard JSONs must be located in the architecture root
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folder. Matching is based on the "EventName" field.
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The PMU events supported by a CPU model are expected to grouped into topics
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such as Pipelining, Cache, Memory, Floating-point etc. All events for a topic
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should be placed in a separate JSON file - where the file name identifies
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the topic. Eg: "Floating-point.json".
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All the topic JSON files for a CPU model/family should be in a separate
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sub directory. Thus for the Silvermont X86 CPU:
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$ ls tools/perf/pmu-events/arch/x86/Silvermont_core
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Cache.json Memory.json Virtual-Memory.json
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Frontend.json Pipeline.json
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The JSONs folder for a CPU model/family may be placed in the root arch
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folder, or may be placed in a vendor sub-folder under the arch folder
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for instances where the arch and vendor are not the same.
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Using the JSON files and the mapfile, 'jevents' generates the C source file,
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'pmu-events.c', which encodes the two sets of tables:
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- Set of 'PMU events tables' for all known CPUs in the architecture,
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(one table like the following, per JSON file; table name 'pme_power8'
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is derived from JSON file name, 'power8.json').
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struct pmu_event pme_power8[] = {
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...
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{
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.name = "pm_1plus_ppc_cmpl",
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.event = "event=0x100f2",
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.desc = "1 or more ppc insts finished,",
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},
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...
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}
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- A 'mapping table' that maps each CPU of the architecture, to its
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'PMU events table'
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struct pmu_events_map pmu_events_map[] = {
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{
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.cpuid = "004b0000",
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.version = "1",
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.type = "core",
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.table = pme_power8
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},
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...
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};
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After the 'pmu-events.c' is generated, it is compiled and the resulting
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'pmu-events.o' is added to 'libperf.a' which is then used to build perf.
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NOTES:
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1. Several CPUs can support same set of events and hence use a common
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JSON file. Hence several entries in the pmu_events_map[] could map
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to a single 'PMU events table'.
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2. The 'pmu-events.h' has an extern declaration for the mapping table
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and the generated 'pmu-events.c' defines this table.
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3. _All_ known CPU tables for architecture are included in the perf
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binary.
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At run time, perf determines the actual CPU it is running on, finds the
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matching events table and builds aliases for those events. This allows
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users to specify events by their name:
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$ perf stat -e pm_1plus_ppc_cmpl sleep 1
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where 'pm_1plus_ppc_cmpl' is a Power8 PMU event.
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However some errors in processing may cause the perf build to fail.
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Mapfile format
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===============
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The mapfile enables multiple CPU models to share a single set of PMU events.
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It is required even if such mapping is 1:1.
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The mapfile.csv format is expected to be:
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Header line
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CPUID,Version,Dir/path/name,Type
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where:
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Comma:
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is the required field delimiter (i.e other fields cannot
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have commas within them).
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Comments:
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Lines in which the first character is either '\n' or '#'
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are ignored.
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Header line
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The header line is the first line in the file, which is
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always _IGNORED_. It can empty.
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CPUID:
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CPUID is an arch-specific char string, that can be used
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to identify CPU (and associate it with a set of PMU events
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it supports). Multiple CPUIDS can point to the same
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File/path/name.json.
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Example:
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CPUID == 'GenuineIntel-6-2E' (on x86).
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CPUID == '004b0100' (PVR value in Powerpc)
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Version:
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is the Version of the mapfile.
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Dir/path/name:
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is the pathname to the directory containing the CPU's JSON
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files, relative to the directory containing the mapfile.csv
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Type:
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indicates whether the events or "core" or "uncore" events.
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Eg:
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$ grep Silvermont tools/perf/pmu-events/arch/x86/mapfile.csv
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GenuineIntel-6-37,V13,Silvermont_core,core
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GenuineIntel-6-4D,V13,Silvermont_core,core
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GenuineIntel-6-4C,V13,Silvermont_core,core
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i.e the three CPU models use the JSON files (i.e PMU events) listed
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in the directory 'tools/perf/pmu-events/arch/x86/Silvermont_core'.
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