[PATCH] perf: cs-etm: Improve missing sink warning message

[PATCH] perf: cs-etm: Improve missing sink warning message

[James Clark]

Make the sink error message more similar to the event error message that
reminds about missing kernel support. The available sinks are also
determined by the hardware so mention that too.

Also, usually it's not necessary to specify the sink, so add that as a
hint.

Now the error for a made up sink looks like this:

  $ perf record -e cs_etm/@abc/
  Couldn't find sink "abc" on event cs_etm/@abc/.
  Missing kernel or device support? Errno: 2 (No such file or directory)

  Hint: An appropriate sink will picked automatically if none is specified.

Signed-off-by: James Clark <james.clark@arm.com>
---
 tools/perf/arch/arm/util/cs-etm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index 481e170cd3f1..c6195a7a3cbf 100644
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -283,7 +283,9 @@ static int cs_etm_set_sink_attr(struct perf_pmu *pmu,
 
 		ret = perf_pmu__scan_file(pmu, path, "%x", &hash);
 		if (ret != 1) {
-			pr_err("failed to set sink \"%s\" on event %s with %d (%s)\n",
+			pr_err("Couldn't find sink \"%s\" on event %s\n"
+			       "Missing kernel or device support? errno: %d (%s)\n\n"
+			       "Hint: An appropriate sink will picked automatically if one isn't specified.\n",
 			       sink, evsel__name(evsel), errno,
 			       str_error_r(errno, msg, sizeof(msg)));
 			return ret;

base-commit: 5670ebf54bd26482f57a094c53bdc562c106e0a9
-- 
2.39.1

Re: [PATCH] perf: cs-etm: Improve missing sink warning message

[Suzuki K Poulose]

On 23/01/2023 16:11, James Clark wrote:
> Make the sink error message more similar to the event error message that
> reminds about missing kernel support. The available sinks are also
> determined by the hardware so mention that too.
> 
> Also, usually it's not necessary to specify the sink, so add that as a
> hint.
> 
> Now the error for a made up sink looks like this:
> 
>    $ perf record -e cs_etm/@abc/
>    Couldn't find sink "abc" on event cs_etm/@abc/.
>    Missing kernel or device support? Errno: 2 (No such file or directory)
> 
>    Hint: An appropriate sink will picked automatically if none is specified.
> 
> Signed-off-by: James Clark <james.clark@arm.com>
> ---
>   tools/perf/arch/arm/util/cs-etm.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
> index 481e170cd3f1..c6195a7a3cbf 100644
> --- a/tools/perf/arch/arm/util/cs-etm.c
> +++ b/tools/perf/arch/arm/util/cs-etm.c
> @@ -283,7 +283,9 @@ static int cs_etm_set_sink_attr(struct perf_pmu *pmu,
>   
>   		ret = perf_pmu__scan_file(pmu, path, "%x", &hash);
>   		if (ret != 1) {
> -			pr_err("failed to set sink \"%s\" on event %s with %d (%s)\n",
> +			pr_err("Couldn't find sink \"%s\" on event %s\n"

Could this be tied to "errno == ENOENT" ?  Otherwise, this could be 
guiding the user to wrong direction.

> +			       "Missing kernel or device support? errno: %d (%s)\n\n"
> +			       "Hint: An appropriate sink will picked automatically if one isn't specified.\n",

minor nit: "... sink will *be* picked.." ?

Otherwise, looks good to me.

Suzuki

>   			       sink, evsel__name(evsel), errno,
>   			       str_error_r(errno, msg, sizeof(msg)));
>   			return ret;
> 
> base-commit: 5670ebf54bd26482f57a094c53bdc562c106e0a9