2022-08-12 11:44:22

by Martin Liška

Subject: [PATCH] perf record: improve error message of -p not_existing_pid

When one uses -p $not_existing_pid, the output of --help is printed:

$ perf record -p 123456789 2>&1 | head -n3

Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]

Let's change it something similar what perf top -p $not_existing_pid
prints:

$ ./perf top -p 123456789 --stdio
Error:
Couldn't create thread/CPU maps: No such process

Newly suggested error message:

$ ./perf record -p 123456789
Couldn't create thread/CPU maps: No such process

Signed-off-by: Martin Liska <[email protected]>
---
tools/perf/builtin-record.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index cf5c5379ceaa..4713f0f3a6cf 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -3996,8 +3996,15 @@ int cmd_record(int argc, const char **argv)
arch__add_leaf_frame_record_opts(&rec->opts);

err = -ENOMEM;
- if (evlist__create_maps(rec->evlist, &rec->opts.target) < 0)
- usage_with_options(record_usage, record_options);
+ if (evlist__create_maps(rec->evlist, &rec->opts.target) < 0) {
+ if (rec->opts.target.pid != NULL) {
+ pr_err("Couldn't create thread/CPU maps: %s\n",
+ errno == ENOENT ? "No such process" : str_error_r(errno, errbuf, sizeof(errbuf)));
+ goto out;
+ }
+ else
+ usage_with_options(record_usage, record_options);
+ }

err = auxtrace_record__options(rec->itr, rec->evlist, &rec->opts);
if (err)
--
2.37.1

2022-08-12 13:55:31

by Arnaldo Carvalho de Melo

Subject: Re: [PATCH] perf record: improve error message of -p not_existing_pid

Em Fri, Aug 12, 2022 at 01:40:49PM +0200, Martin Liška escreveu:
> When one uses -p $not_existing_pid, the output of --help is printed:
>
> $ perf record -p 123456789 2>&1 | head -n3
>
> Usage: perf record [<options>] [<command>]
> or: perf record [<options>] -- <command> [<options>]
>
> Let's change it something similar what perf top -p $not_existing_pid
> prints:
>
> $ ./perf top -p 123456789 --stdio
> Error:
> Couldn't create thread/CPU maps: No such process
>
> Newly suggested error message:
>
> $ ./perf record -p 123456789
> Couldn't create thread/CPU maps: No such process

Thanks, tested and applied.

- Arnaldo


> Signed-off-by: Martin Liska <[email protected]>
> ---
> tools/perf/builtin-record.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index cf5c5379ceaa..4713f0f3a6cf 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -3996,8 +3996,15 @@ int cmd_record(int argc, const char **argv)
> arch__add_leaf_frame_record_opts(&rec->opts);
>
> err = -ENOMEM;
> - if (evlist__create_maps(rec->evlist, &rec->opts.target) < 0)
> - usage_with_options(record_usage, record_options);
> + if (evlist__create_maps(rec->evlist, &rec->opts.target) < 0) {
> + if (rec->opts.target.pid != NULL) {
> + pr_err("Couldn't create thread/CPU maps: %s\n",
> + errno == ENOENT ? "No such process" : str_error_r(errno, errbuf, sizeof(errbuf)));
> + goto out;
> + }
> + else
> + usage_with_options(record_usage, record_options);
> + }
>
> err = auxtrace_record__options(rec->itr, rec->evlist, &rec->opts);
> if (err)
> --
> 2.37.1

--

- Arnaldo