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Message-ID: <20161004003810.GE7143@kernel.org>
Date: Mon, 3 Oct 2016 21:38:10 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
Cc: peterz@...radead.org, maddy@...ux.vnet.ibm.com,
linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v21 15/19] perf, tools: Add README for info on parsing
JSON/map files
Em Thu, Sep 15, 2016 at 03:24:52PM -0700, Sukadev Bhattiprolu escreveu:
> Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
> Acked-by: Jiri Olsa <jolsa@...hat.com>
> Acked-by: Ingo Molnar <mingo@...nel.org>
> ---
> Changelog[v21]
> - Update README to reflect the Topics.json directory tree layout.
Fixed this:
[acme@...et linux]$ am /wb/1.patch
Applying: perf, tools: Add README for info on parsing JSON/map files
.git/rebase-apply/patch:162: new blank line at EOF.
+
warning: 1 line adds whitespace errors.
tools/perf/pmu-events/README:148: new blank line at EOF.
[acme@...et linux]$
> ---
> tools/perf/pmu-events/README | 148 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 148 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..c5ee208e
> --- /dev/null
> +++ b/tools/perf/pmu-events/README
> @@ -0,0 +1,148 @@
> +
> +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.
> +
> + - Regular files with basename starting with 'mapfile.csv' are assumed
> + to be a CSV file that maps a specific CPU to its set of PMU events.
> + (see below for mapfile format)
> +
> + - Directories are traversed, but all other files are ignored.
> +
> +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_core
> + Cache.json Memory.json Virtual-Memory.json
> + Frontend.json Pipeline.json
> +
> +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.
> +
> +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 the 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.
> +
> +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 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 or "core" or "uncore" events.
> +
> +
> + Eg:
> +
> + $ grep Silvermont tools/perf/pmu-events/arch/x86/mapfile.csv
> + GenuineIntel-6-37,V13,Silvermont_core,core
> + GenuineIntel-6-4D,V13,Silvermont_core,core
> + GenuineIntel-6-4C,V13,Silvermont_core,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_core'.
> +
> --
> 1.8.3.1
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