Re: [PATCH] perf data: Allow filtering conversion by start and end time

[Derek Foreman]

On 11/27/25 3:34 PM, Namhyung Kim wrote:
> Hello,
>
> On Mon, Nov 24, 2025 at 03:23:00PM -0600, Derek Foreman wrote:
> > This adds a feature to allow restricting the range of converted samples
> > with start and end times specified in nanoseconds.
> >
> > Use it like this:
> >
> >    $ perf data convert --to-json out.json -s 12345 -e 13340
> >
> > Start, end, or both may be omitted.
> Looks useful, thanks!
Thanks for the review!
> > Signed-off-by: Derek Foreman <derek.foreman@xxxxxxxxxxxxx>
> > ---
> >   tools/perf/Documentation/perf-data.txt |  6 ++++++
> >   tools/perf/builtin-data.c              |  4 ++++
> >   tools/perf/util/data-convert-bt.c      | 18 ++++++++++++++++++
> >   tools/perf/util/data-convert-json.c    | 18 ++++++++++++++++++
> >   tools/perf/util/data-convert.h         |  3 +++
> >   5 files changed, 49 insertions(+)
> >
> > diff --git a/tools/perf/Documentation/perf-data.txt b/tools/perf/Documentation/perf-data.txt
> > index 417bf17e265c..db0de1f354a3 100644
> > --- a/tools/perf/Documentation/perf-data.txt
> > +++ b/tools/perf/Documentation/perf-data.txt
> > @@ -40,6 +40,12 @@ OPTIONS for 'convert'
> >   --force::
> >   	Don't complain, do it.
> >   
> > +-s::
> Please add this as well.
>
> --start=<TIME>::
>
> > +	Start time, in nanoseconds. Samples before this time will not be converted.
> It'd be nice if you mention that users can see the timestamp from perf
> script or so.

After looking at perf script, I realized I'd reinvented the wheel here, 
so in v2 I've used `--time` and the util functions that already exist 
for parsing and filtering time strings.

I mostly copy and pasted the --time help from another file. I think 
asciidoc has a way to templatize this with an include file (it's in at 
least 3 files now), but I wasn't sure if I should try to do that.

> > +
> > +-e::
> --end=<TIME>::
>
> > +	End time, in nanoseconds. Samples after this time will not be converted.
> > +
> >   -v::
> >   --verbose::
> >           Be more verbose (show counter open errors, etc).
> > diff --git a/tools/perf/builtin-data.c b/tools/perf/builtin-data.c
> > index ce51cbf6dc97..da813c62e284 100644
> > --- a/tools/perf/builtin-data.c
> > +++ b/tools/perf/builtin-data.c
> > @@ -33,6 +33,8 @@ const char *to_ctf;
> >   struct perf_data_convert_opts opts = {
> >   	.force = false,
> >   	.all = false,
> > +	.range_start = 0,
> > +	.range_end = 0,
> >   };
> >   
> >   const struct option data_options[] = {
> > @@ -45,6 +47,8 @@ const struct option data_options[] = {
> >   #endif
> >   		OPT_BOOLEAN('f', "force", &opts.force, "don't complain, do it"),
> >   		OPT_BOOLEAN(0, "all", &opts.all, "Convert all events"),
> > +		OPT_U64('s', "start", &opts.range_start, "Earliest timestamp to convert"),
> > +		OPT_U64('e', "end", &opts.range_end, "Latest timestamp to convert"),
> >   		OPT_END()
> >   	};
> >   
> > diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
> > index 3d2e437e1354..6819f11fe900 100644
> > --- a/tools/perf/util/data-convert-bt.c
> > +++ b/tools/perf/util/data-convert-bt.c
> > @@ -91,9 +91,13 @@ struct convert {
> >   	struct perf_tool	tool;
> >   	struct ctf_writer	writer;
> >   
> > +	u64			start;
> > +	u64			end;
> > +
> >   	u64			events_size;
> >   	u64			events_count;
> >   	u64			non_sample_count;
> > +	u64			skipped;
> >   
> >   	/* Ordered events configured queue size. */
> >   	u64			queue_size;
> > @@ -811,6 +815,12 @@ static int process_sample_event(const struct perf_tool *tool,
> >   	if (WARN_ONCE(!priv, "Failed to setup all events.\n"))
> >   		return 0;
> >   
> > +	if (sample->time < c->start ||
> > +	    (c->end && sample->time > c->end)) {
> > +		++c->skipped;
> > +		return 0;
> > +	}
> > +
> >   	event_class = priv->event_class;
> >   
> >   	/* update stats */
> > @@ -1626,6 +1636,9 @@ int bt_convert__perf2ctf(const char *input, const char *path,
> >   	c.tool.namespaces      = perf_event__process_namespaces;
> >   	c.tool.ordering_requires_timestamps = true;
> >   
> > +	c.start = opts->range_start;
> > +	c.end = opts->range_end;
> > +
> >   	if (opts->all) {
> >   		c.tool.comm = process_comm_event;
> >   		c.tool.exit = process_exit_event;
> > @@ -1677,6 +1690,11 @@ int bt_convert__perf2ctf(const char *input, const char *path,
> >   		"[ perf data convert: Converted '%s' into CTF data '%s' ]\n",
> >   		data.path, path);
> >   
> > +	if (c.skipped)
> > +		fprintf(stderr,
> > +			"[ perf data convert: Skipped %" PRIu64 " samples",
> > +			c.skipped);
> This is a strange style to have the literal in a different line.  It'd
> be nice if you can fix others too - probably in a separate commit.
>
> And this line could come after the next, but it's up to you.
I think it's better your way, yes.
> Also it'd be recommended to have a pair of parentheses for multi-line
> bodies even it's a single statement.

I've added a second patch for v2. One of the lines exceeded 100 chars, 
which bothered checkpatch.pl, so I left the literal on the second line 
for now.

Thanks,
Derek

> > +
> >   	fprintf(stderr,
> >   		"[ perf data convert: Converted and wrote %.3f MB (%" PRIu64 " samples",
> >   		(double) c.events_size / 1024.0 / 1024.0,
> > diff --git a/tools/perf/util/data-convert-json.c b/tools/perf/util/data-convert-json.c
> > index 9dc1e184cf3c..dcbba34d6b08 100644
> > --- a/tools/perf/util/data-convert-json.c
> > +++ b/tools/perf/util/data-convert-json.c
> > @@ -35,7 +35,11 @@ struct convert_json {
> >   	struct perf_tool tool;
> >   	FILE *out;
> >   	bool first;
> > +	u64 start;
> > +	u64 end;
> > +
> >   	u64 events_count;
> > +	u64 skipped;
> >   };
> >   
> >   // Outputs a JSON-encoded string surrounded by quotes with characters escaped.
> > @@ -165,6 +169,12 @@ static int process_sample_event(const struct perf_tool *tool,
> >   		return -1;
> >   	}
> >   
> > +	if (sample->time < c->start ||
> > +	    (c->end && sample->time > c->end)) {
> > +		++c->skipped;
> > +		return 0;
> > +	}
> > +
> >   	++c->events_count;
> >   
> >   	if (c->first)
> > @@ -320,6 +330,9 @@ int bt_convert__perf2json(const char *input_name, const char *output_name,
> >   	struct convert_json c = {
> >   		.first = true,
> >   		.events_count = 0,
> > +		.start = opts->range_start,
> > +		.end = opts->range_end,
> > +		.skipped = 0,
> >   	};
> >   	struct perf_data data = {
> >   		.mode = PERF_DATA_MODE_READ,
> > @@ -407,6 +420,11 @@ int bt_convert__perf2json(const char *input_name, const char *output_name,
> >   			"[ perf data convert: Converted '%s' into JSON data '%s' ]\n",
> >   			data.path, output_name);
> >   
> > +	if (c.skipped)
> > +		fprintf(stderr,
> > +				"[ perf data convert: Skipped %" PRIu64 " samples.\n",
> > +				c.skipped);
> Ditto.
>
> Thanks,
> Namhyung
>
> > +
> >   	fprintf(stderr,
> >   			"[ perf data convert: Converted and wrote %.3f MB (%" PRIu64 " samples) ]\n",
> >   			(ftell(c.out)) / 1024.0 / 1024.0, c.events_count);
> > diff --git a/tools/perf/util/data-convert.h b/tools/perf/util/data-convert.h
> > index 1b4c5f598415..5d055e1c31c8 100644
> > --- a/tools/perf/util/data-convert.h
> > +++ b/tools/perf/util/data-convert.h
> > @@ -3,11 +3,14 @@
> >   #define __DATA_CONVERT_H
> >   
> >   #include <stdbool.h>
> > +#include <linux/types.h>
> >   
> >   struct perf_data_convert_opts {
> >   	bool force;
> >   	bool all;
> >   	bool tod;
> > +	u64 range_start;
> > +	u64 range_end;
> >   };
> >   
> >   #ifdef HAVE_LIBBABELTRACE_SUPPORT
> > --
> > 2.47.3