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Date:   Mon, 26 Apr 2021 18:24:28 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Nicholas Fraser <nfraser@codeweavers.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Ian Rogers <irogers@google.com>,
        Changbin Du <changbin.du@intel.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Tan Xiaojun <tanxiaojun@huawei.com>,
        Jin Yao <yao.jin@linux.intel.com>,
        linux-kernel@vger.kernel.org,
        Ulrich Czekalla <uczekalla@codeweavers.com>
Subject: Re: [PATCH v2] perf data: Add JSON export
Message-ID: <YIcvjFr/hN2Syybc@kernel.org>
References: <3884969f-804d-2f53-c648-e2b0bd85edff@codeweavers.com>
 <YIch1aRwL4Lk7iWJ@kernel.org>
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In-Reply-To: <YIch1aRwL4Lk7iWJ@kernel.org>
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Em Mon, Apr 26, 2021 at 05:25:58PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Mon, Apr 26, 2021 at 10:47:16AM -0400, Nicholas Fraser escreveu:
> > 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

One more, clang complains:

   7    50.92 alpine:3.10                   : FAIL gcc version 8.3.0 (Alpine 8.3.0)
    util/data-convert-json.c:126:32: error: address of array 'al->sym->name' will always evaluate to 'true' [-Werror,-Wpointer-bool-conversion]
            if (al && al->sym && al->sym->name && strlen(al->sym->name) > 0) {
                              ~~ ~~~~~~~~~^~~~
    1 error generated.
    make[3]: *** [/git/perf-5.12.0/tools/build/Makefile.build:139: util] Error 2

 
> I had to apply this for it to build:
> 
> diff --git a/tools/perf/util/data-convert-json.c b/tools/perf/util/data-convert-json.c
> index b57c48d355039f6f..f24593d57f80be1b 100644
> --- a/tools/perf/util/data-convert-json.c
> +++ b/tools/perf/util/data-convert-json.c
> @@ -100,7 +100,7 @@ static void output_json_key_string(FILE *out, bool comma, int depth,
>  }
> 
>  // Outputs a JSON key-value pair where the value is a printf format string.
> -__(printf, 5, 6)
> +__printf(5, 6)
>  static void output_json_key_format(FILE *out, bool comma, int depth,
>                 const char *key, const char *format, ...)
>  {
> [acme@five perf]$
> 
> I'll test build with the container suite and test the feature, thanks!
> 
> - Arnaldo
>  
> > Signed-off-by: Nicholas Fraser <nfraser@codeweavers.com>
> > ---
> > 
> > Notes:
> >     This is a follow-up to a patch sent a couple weeks ago. I realized I sent a
> >     fixed version incorrectly as a reply to a previous version of the same patch so
> >     I'm re-sending it properly.
> >     
> >     Here's an example of what the resulting JSON looks like:
> >     
> >     {
> >             "linux-perf-json-version": 1,
> >             "headers": {
> >                     "header-version": 1,
> >                     "captured-on": "2021-04-06T08:42:01Z",
> >                     "os-release": "5.11.11-arch1-1",
> >                     "arch": "x86_64",
> >                     "cpu-desc": "Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz",
> >                     ...
> >             },
> >             "samples": [
> >                     {
> >                             "timestamp": 3074717308597,
> >                             "pid": 8604,
> >                             "tid": 8604,
> >                             "comm": "sh",
> >                             "callchain": [
> >                                     {
> >                                             "ip": "0x7f1e0deb2d36",
> >                                             "symbol": "__strcmp_avx2",
> >                                             "dso": "libc-2.33.so"
> >                                     },
> >                                     {
> >                                             "ip": "0x7f1e0dd7f49f",
> >                                             "symbol": "__gconv_find_transform",
> >                                             "dso": "libc-2.33.so"
> >                                     },
> >                                     ...
> >                             ]
> >                     },
> >                     ...
> >             ]
> >     }
> >     
> >     The JSON is of course huge but it compresses well. It can be piped directly to
> >     a compressor, for example:
> >     
> >     perf data convert --to-json /dev/stdout | xz > out.json.xz
> > 
> >  tools/perf/Documentation/perf-data.txt |   5 +-
> >  tools/perf/builtin-data.c              |  26 +-
> >  tools/perf/util/Build                  |   1 +
> >  tools/perf/util/data-convert-bt.c      |   2 +-
> >  tools/perf/util/data-convert-bt.h      |  11 -
> >  tools/perf/util/data-convert-json.c    | 384 +++++++++++++++++++++++++
> >  tools/perf/util/data-convert.h         |  10 +
> >  7 files changed, 418 insertions(+), 21 deletions(-)
> >  delete mode 100644 tools/perf/util/data-convert-bt.h
> >  create mode 100644 tools/perf/util/data-convert-json.c
> > 
> > diff --git a/tools/perf/Documentation/perf-data.txt b/tools/perf/Documentation/perf-data.txt
> > index 726b9bc9e1a7..417bf17e265c 100644
> > --- a/tools/perf/Documentation/perf-data.txt
> > +++ b/tools/perf/Documentation/perf-data.txt
> > @@ -17,7 +17,7 @@ Data file related processing.
> >  COMMANDS
> >  --------
> >  convert::
> > -	Converts perf data file into another format (only CTF [1] format is support by now).
> > +	Converts perf data file into another format.
> >  	It's possible to set data-convert debug variable to get debug messages from conversion,
> >  	like:
> >  	  perf --debug data-convert data convert ...
> > @@ -27,6 +27,9 @@ OPTIONS for 'convert'
> >  --to-ctf::
> >  	Triggers the CTF conversion, specify the path of CTF data directory.
> >  
> > +--to-json::
> > +	Triggers JSON conversion. Specify the JSON filename to output.
> > +
> >  --tod::
> >  	Convert time to wall clock time.
> >  
> > diff --git a/tools/perf/builtin-data.c b/tools/perf/builtin-data.c
> > index 8d23b8d6ee8e..15ca23675ef0 100644
> > --- a/tools/perf/builtin-data.c
> > +++ b/tools/perf/builtin-data.c
> > @@ -7,7 +7,6 @@
> >  #include "debug.h"
> >  #include <subcmd/parse-options.h>
> >  #include "data-convert.h"
> > -#include "data-convert-bt.h"
> >  
> >  typedef int (*data_cmd_fn_t)(int argc, const char **argv);
> >  
> > @@ -55,7 +54,8 @@ static const char * const data_convert_usage[] = {
> >  
> >  static int cmd_data_convert(int argc, const char **argv)
> >  {
> > -	const char *to_ctf     = NULL;
> > +	const char *to_json = NULL;
> > +	const char *to_ctf = NULL;
> >  	struct perf_data_convert_opts opts = {
> >  		.force = false,
> >  		.all = false,
> > @@ -63,6 +63,7 @@ static int cmd_data_convert(int argc, const char **argv)
> >  	const struct option options[] = {
> >  		OPT_INCR('v', "verbose", &verbose, "be more verbose"),
> >  		OPT_STRING('i', "input", &input_name, "file", "input file name"),
> > +		OPT_STRING(0, "to-json", &to_json, NULL, "Convert to JSON format"),
> >  #ifdef HAVE_LIBBABELTRACE_SUPPORT
> >  		OPT_STRING(0, "to-ctf", &to_ctf, NULL, "Convert to CTF format"),
> >  		OPT_BOOLEAN(0, "tod", &opts.tod, "Convert time to wall clock time"),
> > @@ -72,11 +73,6 @@ static int cmd_data_convert(int argc, const char **argv)
> >  		OPT_END()
> >  	};
> >  
> > -#ifndef HAVE_LIBBABELTRACE_SUPPORT
> > -	pr_err("No conversion support compiled in. perf should be compiled with environment variables LIBBABELTRACE=1 and LIBBABELTRACE_DIR=/path/to/libbabeltrace/\n");
> > -	return -1;
> > -#endif
> > -
> >  	argc = parse_options(argc, argv, options,
> >  			     data_convert_usage, 0);
> >  	if (argc) {
> > @@ -84,11 +80,25 @@ static int cmd_data_convert(int argc, const char **argv)
> >  		return -1;
> >  	}
> >  
> > +	if (to_json && to_ctf) {
> > +		pr_err("You cannot specify both --to-ctf and --to-json.\n");
> > +		return -1;
> > +	}
> > +	if (!to_json && !to_ctf) {
> > +		pr_err("You must specify one of --to-ctf or --to-json.\n");
> > +		return -1;
> > +	}
> > +
> > +	if (to_json)
> > +		return bt_convert__perf2json(input_name, to_json, &opts);
> > +
> >  	if (to_ctf) {
> >  #ifdef HAVE_LIBBABELTRACE_SUPPORT
> >  		return bt_convert__perf2ctf(input_name, to_ctf, &opts);
> >  #else
> > -		pr_err("The libbabeltrace support is not compiled in.\n");
> > +		pr_err("The libbabeltrace support is not compiled in. perf should be "
> > +		       "compiled with environment variables LIBBABELTRACE=1 and "
> > +		       "LIBBABELTRACE_DIR=/path/to/libbabeltrace/\n");
> >  		return -1;
> >  #endif
> >  	}
> > diff --git a/tools/perf/util/Build b/tools/perf/util/Build
> > index e2563d0154eb..de9ac182b25a 100644
> > --- a/tools/perf/util/Build
> > +++ b/tools/perf/util/Build
> > @@ -163,6 +163,7 @@ perf-$(CONFIG_LIBUNWIND_X86)      += libunwind/x86_32.o
> >  perf-$(CONFIG_LIBUNWIND_AARCH64)  += libunwind/arm64.o
> >  
> >  perf-$(CONFIG_LIBBABELTRACE) += data-convert-bt.o
> > +perf-y += data-convert-json.o
> >  
> >  perf-y += scripting-engines/
> >  
> > diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
> > index 27c5fef9ad54..803102207a8b 100644
> > --- a/tools/perf/util/data-convert-bt.c
> > +++ b/tools/perf/util/data-convert-bt.c
> > @@ -21,7 +21,7 @@
> >  #include <babeltrace/ctf/events.h>
> >  #include <traceevent/event-parse.h>
> >  #include "asm/bug.h"
> > -#include "data-convert-bt.h"
> > +#include "data-convert.h"
> >  #include "session.h"
> >  #include "debug.h"
> >  #include "tool.h"
> > diff --git a/tools/perf/util/data-convert-bt.h b/tools/perf/util/data-convert-bt.h
> > deleted file mode 100644
> > index 821674d63c4e..000000000000
> > --- a/tools/perf/util/data-convert-bt.h
> > +++ /dev/null
> > @@ -1,11 +0,0 @@
> > -/* SPDX-License-Identifier: GPL-2.0 */
> > -#ifndef __DATA_CONVERT_BT_H
> > -#define __DATA_CONVERT_BT_H
> > -#include "data-convert.h"
> > -#ifdef HAVE_LIBBABELTRACE_SUPPORT
> > -
> > -int bt_convert__perf2ctf(const char *input_name, const char *to_ctf,
> > -			 struct perf_data_convert_opts *opts);
> > -
> > -#endif /* HAVE_LIBBABELTRACE_SUPPORT */
> > -#endif /* __DATA_CONVERT_BT_H */
> > diff --git a/tools/perf/util/data-convert-json.c b/tools/perf/util/data-convert-json.c
> > new file mode 100644
> > index 000000000000..b57c48d35503
> > --- /dev/null
> > +++ b/tools/perf/util/data-convert-json.c
> > @@ -0,0 +1,384 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * JSON export.
> > + *
> > + * Copyright (C) 2021, CodeWeavers Inc. <nfraser@codeweavers.com>
> > + */
> > +
> > +#include "data-convert.h"
> > +
> > +#include <fcntl.h>
> > +#include <inttypes.h>
> > +#include <sys/stat.h>
> > +#include <unistd.h>
> > +
> > +#include "linux/compiler.h"
> > +#include "linux/err.h"
> > +#include "util/auxtrace.h"
> > +#include "util/debug.h"
> > +#include "util/dso.h"
> > +#include "util/event.h"
> > +#include "util/evsel.h"
> > +#include "util/evlist.h"
> > +#include "util/header.h"
> > +#include "util/map.h"
> > +#include "util/session.h"
> > +#include "util/symbol.h"
> > +#include "util/thread.h"
> > +#include "util/tool.h"
> > +
> > +struct convert_json {
> > +	struct perf_tool tool;
> > +	FILE *out;
> > +	bool first;
> > +	u64 events_count;
> > +};
> > +
> > +// Outputs a JSON-encoded string surrounded by quotes with characters escaped.
> > +static void output_json_string(FILE *out, const char *s)
> > +{
> > +	fputc('"', out);
> > +	while (*s) {
> > +		switch (*s) {
> > +
> > +		// required escapes with special forms as per RFC 8259
> > +		case '"':  fputs("\\\"", out); break;
> > +		case '\\': fputs("\\\\", out); break;
> > +		case '\b': fputs("\\b", out);  break;
> > +		case '\f': fputs("\\f", out);  break;
> > +		case '\n': fputs("\\n", out);  break;
> > +		case '\r': fputs("\\r", out);  break;
> > +		case '\t': fputs("\\t", out);  break;
> > +
> > +		default:
> > +			// all other control characters must be escaped by hex code
> > +			if (*s <= 0x1f)
> > +				fprintf(out, "\\u%04x", *s);
> > +			else
> > +				fputc(*s, out);
> > +			break;
> > +		}
> > +
> > +		++s;
> > +	}
> > +	fputc('"', out);
> > +}
> > +
> > +// Outputs an optional comma, newline and indentation to delimit a new value
> > +// from the previous one in a JSON object or array.
> > +static void output_json_delimiters(FILE *out, bool comma, int depth)
> > +{
> > +	int i;
> > +
> > +	if (comma)
> > +		fputc(',', out);
> > +	fputc('\n', out);
> > +	for (i = 0; i < depth; ++i)
> > +		fputc('\t', out);
> > +}
> > +
> > +// Outputs a printf format string (with delimiter) as a JSON value.
> > +__printf(4, 5)
> > +static void output_json_format(FILE *out, bool comma, int depth, const char *format, ...)
> > +{
> > +	va_list args;
> > +
> > +	output_json_delimiters(out, comma, depth);
> > +	va_start(args, format);
> > +	vfprintf(out,  format, args);
> > +	va_end(args);
> > +}
> > +
> > +// Outputs a JSON key-value pair where the value is a string.
> > +static void output_json_key_string(FILE *out, bool comma, int depth,
> > +		const char *key, const char *value)
> > +{
> > +	output_json_delimiters(out, comma, depth);
> > +	output_json_string(out, key);
> > +	fputs(": ", out);
> > +	output_json_string(out, value);
> > +}
> > +
> > +// Outputs a JSON key-value pair where the value is a printf format string.
> > +__(printf, 5, 6)
> > +static void output_json_key_format(FILE *out, bool comma, int depth,
> > +		const char *key, const char *format, ...)
> > +{
> > +	va_list args;
> > +
> > +	output_json_delimiters(out, comma, depth);
> > +	output_json_string(out, key);
> > +	fputs(": ", out);
> > +	va_start(args, format);
> > +	vfprintf(out,  format, args);
> > +	va_end(args);
> > +}
> > +
> > +static void output_sample_callchain_entry(struct perf_tool *tool,
> > +		u64 ip, struct addr_location *al)
> > +{
> > +	struct convert_json *c = container_of(tool, struct convert_json, tool);
> > +	FILE *out = c->out;
> > +
> > +	output_json_format(out, false, 4, "{");
> > +	output_json_key_format(out, false, 5, "ip", "\"0x%" PRIx64 "\"", ip);
> > +
> > +	if (al && al->sym && al->sym->name && strlen(al->sym->name) > 0) {
> > +		fputc(',', out);
> > +		output_json_key_string(out, false, 5, "symbol", al->sym->name);
> > +
> > +		if (al->map && al->map->dso) {
> > +			const char *dso = al->map->dso->short_name;
> > +
> > +			if (dso && strlen(dso) > 0) {
> > +				fputc(',', out);
> > +				output_json_key_string(out, false, 5, "dso", dso);
> > +			}
> > +		}
> > +	}
> > +
> > +	output_json_format(out, false, 4, "}");
> > +}
> > +
> > +static int process_sample_event(struct perf_tool *tool,
> > +				union perf_event *event __maybe_unused,
> > +				struct perf_sample *sample,
> > +				struct evsel *evsel __maybe_unused,
> > +				struct machine *machine)
> > +{
> > +	struct convert_json *c = container_of(tool, struct convert_json, tool);
> > +	FILE *out = c->out;
> > +	struct addr_location al, tal;
> > +	u8 cpumode = PERF_RECORD_MISC_USER;
> > +
> > +	if (machine__resolve(machine, &al, sample) < 0) {
> > +		pr_err("Sample resolution failed!\n");
> > +		return -1;
> > +	}
> > +
> > +	++c->events_count;
> > +
> > +	if (c->first)
> > +		c->first = false;
> > +	else
> > +		fputc(',', out);
> > +	output_json_format(out, false, 2, "{");
> > +
> > +	output_json_key_format(out, false, 3, "timestamp", "%" PRIi64, sample->time);
> > +	output_json_key_format(out, true, 3, "pid", "%i", al.thread->pid_);
> > +	output_json_key_format(out, true, 3, "tid", "%i", al.thread->tid);
> > +
> > +	if (al.thread->cpu >= 0)
> > +		output_json_key_format(out, true, 3, "cpu", "%i", al.thread->cpu);
> > +
> > +	output_json_key_string(out, true, 3, "comm", thread__comm_str(al.thread));
> > +
> > +	output_json_key_format(out, true, 3, "callchain", "[");
> > +	if (sample->callchain) {
> > +		unsigned int i;
> > +		bool ok;
> > +		bool first_callchain = true;
> > +
> > +		for (i = 0; i < sample->callchain->nr; ++i) {
> > +			u64 ip = sample->callchain->ips[i];
> > +
> > +			if (ip >= PERF_CONTEXT_MAX) {
> > +				switch (ip) {
> > +				case PERF_CONTEXT_HV:
> > +					cpumode = PERF_RECORD_MISC_HYPERVISOR;
> > +					break;
> > +				case PERF_CONTEXT_KERNEL:
> > +					cpumode = PERF_RECORD_MISC_KERNEL;
> > +					break;
> > +				case PERF_CONTEXT_USER:
> > +					cpumode = PERF_RECORD_MISC_USER;
> > +					break;
> > +				default:
> > +					pr_debug("invalid callchain context: %"
> > +							PRId64 "\n", (s64) ip);
> > +					break;
> > +				}
> > +				continue;
> > +			}
> > +
> > +			if (first_callchain)
> > +				first_callchain = false;
> > +			else
> > +				fputc(',', out);
> > +
> > +			ok = thread__find_symbol(al.thread, cpumode, ip, &tal);
> > +			output_sample_callchain_entry(tool, ip, ok ? &tal : NULL);
> > +		}
> > +	} else {
> > +		output_sample_callchain_entry(tool, sample->ip, &al);
> > +	}
> > +	output_json_format(out, false, 3, "]");
> > +
> > +	output_json_format(out, false, 2, "}");
> > +	return 0;
> > +}
> > +
> > +static void output_headers(struct perf_session *session, struct convert_json *c)
> > +{
> > +	struct stat st;
> > +	struct perf_header *header = &session->header;
> > +	int ret;
> > +	int fd = perf_data__fd(session->data);
> > +	int i;
> > +	FILE *out = c->out;
> > +
> > +	output_json_key_format(out, false, 2, "header-version", "%u", header->version);
> > +
> > +	ret = fstat(fd, &st);
> > +	if (ret >= 0) {
> > +		time_t stctime = st.st_mtime;
> > +		char buf[256];
> > +
> > +		strftime(buf, sizeof(buf), "%FT%TZ", gmtime(&stctime));
> > +		output_json_key_string(out, true, 2, "captured-on", buf);
> > +	} else {
> > +		pr_debug("Failed to get mtime of source file, not writing captured-on");
> > +	}
> > +
> > +	output_json_key_format(out, true, 2, "data-offset", "%" PRIu64, header->data_offset);
> > +	output_json_key_format(out, true, 2, "data-size", "%" PRIu64, header->data_size);
> > +	output_json_key_format(out, true, 2, "feat-offset", "%" PRIu64, header->feat_offset);
> > +
> > +	output_json_key_string(out, true, 2, "hostname", header->env.hostname);
> > +	output_json_key_string(out, true, 2, "os-release", header->env.os_release);
> > +	output_json_key_string(out, true, 2, "arch", header->env.arch);
> > +
> > +	output_json_key_string(out, true, 2, "cpu-desc", header->env.cpu_desc);
> > +	output_json_key_string(out, true, 2, "cpuid", header->env.cpuid);
> > +	output_json_key_format(out, true, 2, "nrcpus-online", "%u", header->env.nr_cpus_online);
> > +	output_json_key_format(out, true, 2, "nrcpus-avail", "%u", header->env.nr_cpus_avail);
> > +
> > +	if (header->env.clock.enabled) {
> > +		output_json_key_format(out, true, 2, "clockid",
> > +				"%u", header->env.clock.clockid);
> > +		output_json_key_format(out, true, 2, "clock-time",
> > +				"%" PRIu64, header->env.clock.clockid_ns);
> > +		output_json_key_format(out, true, 2, "real-time",
> > +				"%" PRIu64, header->env.clock.tod_ns);
> > +	}
> > +
> > +	output_json_key_string(out, true, 2, "perf-version", header->env.version);
> > +
> > +	output_json_key_format(out, true, 2, "cmdline", "[");
> > +	for (i = 0; i < header->env.nr_cmdline; i++) {
> > +		output_json_delimiters(out, i != 0, 3);
> > +		output_json_string(c->out, header->env.cmdline_argv[i]);
> > +	}
> > +	output_json_format(out, false, 2, "]");
> > +}
> > +
> > +int bt_convert__perf2json(const char *input_name, const char *output_name,
> > +		struct perf_data_convert_opts *opts __maybe_unused)
> > +{
> > +	struct perf_session *session;
> > +	int fd;
> > +	int ret = -1;
> > +
> > +	struct convert_json c = {
> > +		.tool = {
> > +			.sample         = process_sample_event,
> > +			.mmap           = perf_event__process_mmap,
> > +			.mmap2          = perf_event__process_mmap2,
> > +			.comm           = perf_event__process_comm,
> > +			.namespaces     = perf_event__process_namespaces,
> > +			.cgroup         = perf_event__process_cgroup,
> > +			.exit           = perf_event__process_exit,
> > +			.fork           = perf_event__process_fork,
> > +			.lost           = perf_event__process_lost,
> > +			.tracing_data   = perf_event__process_tracing_data,
> > +			.build_id       = perf_event__process_build_id,
> > +			.id_index       = perf_event__process_id_index,
> > +			.auxtrace_info  = perf_event__process_auxtrace_info,
> > +			.auxtrace       = perf_event__process_auxtrace,
> > +			.event_update   = perf_event__process_event_update,
> > +			.ordered_events = true,
> > +			.ordering_requires_timestamps = true,
> > +		},
> > +		.first = true,
> > +		.events_count = 0,
> > +	};
> > +
> > +	struct perf_data data = {
> > +		.mode = PERF_DATA_MODE_READ,
> > +		.path = input_name,
> > +		.force = opts->force,
> > +	};
> > +
> > +	if (opts->all) {
> > +		pr_err("--all is currently unsupported for JSON output.\n");
> > +		goto err;
> > +	}
> > +	if (opts->tod) {
> > +		pr_err("--tod is currently unsupported for JSON output.\n");
> > +		goto err;
> > +	}
> > +
> > +	fd = open(output_name, O_CREAT | O_WRONLY | (opts->force ? O_TRUNC : O_EXCL), 0666);
> > +	if (fd == -1) {
> > +		if (errno == EEXIST)
> > +			pr_err("Output file exists. Use --force to overwrite it.\n");
> > +		else
> > +			pr_err("Error opening output file!\n");
> > +		goto err;
> > +	}
> > +
> > +	c.out = fdopen(fd, "w");
> > +	if (!c.out) {
> > +		fprintf(stderr, "Error opening output file!\n");
> > +		close(fd);
> > +		goto err;
> > +	}
> > +
> > +	session = perf_session__new(&data, false, &c.tool);
> > +	if (IS_ERR(session)) {
> > +		fprintf(stderr, "Error creating perf session!\n");
> > +		goto err_fclose;
> > +	}
> > +
> > +	if (symbol__init(&session->header.env) < 0) {
> > +		fprintf(stderr, "Symbol init error!\n");
> > +		goto err_session_delete;
> > +	}
> > +
> > +	// The opening brace is printed manually because it isn't delimited from a
> > +	// previous value (i.e. we don't want a leading newline)
> > +	fputc('{', c.out);
> > +
> > +	// Version number for future-proofing. Most additions should be able to be
> > +	// done in a backwards-compatible way so this should only need to be bumped
> > +	// if some major breaking change must be made.
> > +	output_json_format(c.out, false, 1, "\"linux-perf-json-version\": 1");
> > +
> > +	// Output headers
> > +	output_json_format(c.out, true, 1, "\"headers\": {");
> > +	output_headers(session, &c);
> > +	output_json_format(c.out, false, 1, "}");
> > +
> > +	// Output samples
> > +	output_json_format(c.out, true, 1, "\"samples\": [");
> > +	perf_session__process_events(session);
> > +	output_json_format(c.out, false, 1, "]");
> > +	output_json_format(c.out, false, 0, "}");
> > +	fputc('\n', c.out);
> > +
> > +	fprintf(stderr,
> > +			"[ perf data convert: Converted '%s' into JSON data '%s' ]\n",
> > +			data.path, output_name);
> > +
> > +	fprintf(stderr,
> > +			"[ perf data convert: Converted and wrote %.3f MB (%" PRIu64 " samples) ]\n",
> > +			(ftell(c.out)) / 1024.0 / 1024.0, c.events_count);
> > +
> > +	ret = 0;
> > +err_session_delete:
> > +	perf_session__delete(session);
> > +err_fclose:
> > +	fclose(c.out);
> > +err:
> > +	return ret;
> > +}
> > diff --git a/tools/perf/util/data-convert.h b/tools/perf/util/data-convert.h
> > index feab5f114e37..1b4c5f598415 100644
> > --- a/tools/perf/util/data-convert.h
> > +++ b/tools/perf/util/data-convert.h
> > @@ -2,10 +2,20 @@
> >  #ifndef __DATA_CONVERT_H
> >  #define __DATA_CONVERT_H
> >  
> > +#include <stdbool.h>
> > +
> >  struct perf_data_convert_opts {
> >  	bool force;
> >  	bool all;
> >  	bool tod;
> >  };
> >  
> > +#ifdef HAVE_LIBBABELTRACE_SUPPORT
> > +int bt_convert__perf2ctf(const char *input_name, const char *to_ctf,
> > +			 struct perf_data_convert_opts *opts);
> > +#endif /* HAVE_LIBBABELTRACE_SUPPORT */
> > +
> > +int bt_convert__perf2json(const char *input_name, const char *to_ctf,
> > +			 struct perf_data_convert_opts *opts);
> > +
> >  #endif /* __DATA_CONVERT_H */
> > -- 
> > 2.31.1
> > 
> 
> -- 
> 
> - Arnaldo

-- 

- Arnaldo