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perf data: Add JSON export
Nicholas Fraser authored
This adds a feature to export perf data to JSON.

The resolved symbols are exported into the JSON so that external tools
don't need to load the dsos themselves (or even have access to them at
all.) This makes it easy to load and analyze perf data with standalone
tools where direct perf or libbabeltrace integration is impractical.

The exporter uses a minimal inline JSON encoding without any external
dependencies. Currently it only outputs some headers and sample metadata
but it's easily extensible.

Use it like this:

  $ perf data convert --to-json out.json

Committer notes:

Fixup a __printf() bug that broke the build:

  util/data-convert-json.c:103:11: error: expected ‘)’ before numeric constant
    103 | __(printf, 5, 6)
        |           ^~
        |           )
  util/data-convert-json.c: In function ‘output_sample_callchain_entry’:
  util/data-convert-json.c:124:2: error: implicit declaration of function ‘output_json_key_format’; did you mean ‘output_json_format’? [-Werror=implicit-function-declaration]
    124 |  output_json_key_format(out, false, 5, "ip", "\"0x%" PRIx64 "\"", ip);
        |  ^~~~~~~~~~~~~~~~~~~~~~
        |  output_json_format

Also had to add this patch to fix errors reported by various versions of
clang:

  -       if (al && al->sym && al->sym->name && strlen(al->sym->name) > 0) {
  +       if (al && al->sym && al->sym->namelen) {

al->sym->name is a zero sized array, to avoid one extra alloc in the
symbol__new() constructor, sym->namelen carries its strlen.

Committer testing:

  $ ls -la out.json
  ls: cannot access 'out.json': No such file or directory
  $ perf record sleep 0.1
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.001 MB perf.data (8 samples) ]
  $ perf report --stats | grep -w SAMPLE
            SAMPLE events:          8
  $ perf data convert --to-json out.json
  [ perf data convert: Converted 'perf.data' into JSON data 'out.json' ]
  [ perf data convert: Converted and wrote 0.002 MB (8 samples) ]
  $ ls -la out.json
  -rw-rw-r--. 1 acme acme 2017 Apr 26 17:29 out.json
  $ cat out.json
  {
  	"linux-perf-json-version": 1,
  	"headers": {
  		"header-version": 1,
  		"captured-on": "2021-04-26T20:28:57Z",
  		"data-offset": 432,
  		"data-size": 1016,
  		"feat-offset": 1448,
  		"hostname": "five",
  		"os-release": "5.11.14-200.fc33.x86_64",
  		"arch": "x86_64",
  		"cpu-desc": "AMD Ryzen 9 3900X 12-Core Processor",
  		"cpuid": "AuthenticAMD,23,113,0",
  		"nrcpus-online": 24,
  		"nrcpus-avail": 24,
  		"perf-version": "5.12.gee134f3189bd",
  		"cmdline": [
  			"/home/acme/bin/perf",
  			"record",
  			"sleep",
  			"0.1"
  		]
  	},
  	"samples": [
  		{
  			"timestamp": 170517539043684,
  			"pid": 375844,
  			"tid": 375844,
  			"comm": "sleep",
  			"callchain": [
  				{
  					"ip": "0xffffffffa6268827"
  				}
  			]
  		},
  		{
  			"timestamp": 170517539048443,
  			"pid": 375844,
  			"tid": 375844,
  			"comm": "sleep",
  			"callchain": [
  				{
  					"ip": "0xffffffffa661359d"
  				}
  			]
  		},
  		{
  			"timestamp": 170517539051018,
  			"pid": 375844,
  			"tid": 375844,
  			"comm": "sleep",
  			"callchain": [
  				{
  					"ip": "0xffffffffa6311e18"
  				}
  			]
  		},
  		{
  			"timestamp": 170517539053652,
  			"pid": 375844,
  			"tid": 375844,
  			"comm": "sleep",
  			"callchain": [
  				{
  					"ip": "0x7fdb77b4812b",
  					"symbol": "_dl_start",
  					"dso": "ld-2.32.so"
  				}
  			]
  		},
  		{
  			"timestamp": 170517539055306,
  			"pid": 375844,
  			"tid": 375844,
  			"comm": "sleep",
  			"callchain": [
  				{
  					"ip": "0xffffffffa6269286"
  				}
  			]
  		},
  		{
  			"timestamp": 170517539057590,
  			"pid": 375844,
  			"tid": 375844,
  			"comm": "sleep",
  			"callchain": [
  				{
  					"ip": "0xffffffffa62abd8b"
  				}
  			]
  		},
  		{
  			"timestamp": 170517539067559,
  			"pid": 375844,
  			"tid": 375844,
  			"comm": "sleep",
  			"callchain": [
  				{
  					"ip": "0x7fdb77b5e9e9",
  					"symbol": "__GI___tunables_init",
  					"dso": "ld-2.32.so"
  				}
  			]
  		},
  		{
  			"timestamp": 170517539282452,
  			"pid": 375844,
  			"tid": 375844,
  			"comm": "sleep",
  			"callchain": [
  				{
  					"ip": "0x7fdb779978d2",
  					"symbol": "getenv",
  					"dso": "libc-2.32.so"
  				}
  			]
  		}
  	]
  }
  $
Signed-off-by: default avatarNicholas Fraser <nfraser@codeweavers.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tan Xiaojun <tanxiaojun@huawei.com>
Cc: Ulrich Czekalla <uczekalla@codeweavers.com>
Link: http://lore.kernel.org/lkml/3884969f-804d-2f53-c648-e2b0bd85edff@codeweavers.com

Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
d0713d4c
Name Last commit Last update
..
arm-spe-decoder perf arm-spe: Avoid potential buffer overrun
bpf_skel perf stat: Introduce 'bperf' to share hardware PMCs with BPF
c++ perf clang: Fix build with Clang 9
cs-etm-decoder perf tools: Fix various typos in comments
include tools arch: Update arch/x86/lib/mem{cpy,set}_64.S copies used in 'perf bench mem memcpy'
intel-pt-decoder perf intel-pt: Amend decoder to track the NR flag
libunwind perf tools: Fix various typos in comments
scripting-engines perf tools: Fix various typos in comments
Build perf data: Add JSON export
PERF-VERSION-GEN perf version: Append 12 git SHA chars to the version string
affinity.c perf affinity: Add infrastructure to save/restore affinity
affinity.h perf affinity: Add infrastructure to save/restore affinity
annotate.c perf annotate: Add line number like in TUI and source location at EOL
annotate.h perf annotate: Show full source location with 'l' hotkey
archinsn.h perf script: Support insn output for normal samples
arm-spe.c perf arm-spe: Set sample's data source field
arm-spe.h perf tools: Add ARM Statistical Profiling Extensions (SPE) support
auxtrace.c perf auxtrace: Fix potential NULL pointer dereference
auxtrace.h perf auxtrace: Automatically group aux-output events
block-info.c perf report: Fix wrong LBR block sorting
block-info.h perf block-info: Allow selecting which columns to report and its order
block-range.c perf block-range: Add missing headers
block-range.h perf block-range: Add missing headers
bpf-event.c perf top: Fix BPF support related crash with perf_event_paranoid=3 + kptr_restrict
bpf-event.h perf bpf: Decouple creating the evlist from adding the SB event
bpf-loader.c
bpf-loader.h
bpf-prologue.c
bpf-prologue.h
bpf_counter.c
bpf_counter.h
bpf_map.c
bpf_map.h
branch.c
branch.h
build-id.c
build-id.h
cache.h
cacheline.c
cacheline.h
call-path.c
call-path.h
callchain.c
callchain.h
cap.c
cap.h
cgroup.c
cgroup.h
clockid.c
clockid.h
cloexec.c
cloexec.h
color.c
color.h
color_config.c
comm.c
comm.h
compress.h
config.c
config.h
copyfile.c
copyfile.h
counts.c
counts.h
cpu-set-sched.h
cpumap.c
cpumap.h
cputopo.c
cputopo.h
cs-etm.c
cs-etm.h
data-convert-bt.c
data-convert-json.c
data-convert.h
data.c
data.h
db-export.c
db-export.h
debug.c
debug.h
demangle-java.c
demangle-java.h
demangle-ocaml.c
demangle-ocaml.h
demangle-rust.c
demangle-rust.h
dso.c
dso.h
dsos.c
dsos.h
dump-insn.c
dump-insn.h
dwarf-aux.c
dwarf-aux.h
dwarf-regs.c
env.c
env.h
event.c
event.h
events_stats.h