* [PATCH] tools/perf: Fix usage of perf probe when libtraceevent is missing
@ 2023-01-31 13:47 Athira Rajeev
2023-02-02 0:50 ` Arnaldo Carvalho de Melo
0 siblings, 1 reply; 3+ messages in thread
From: Athira Rajeev @ 2023-01-31 13:47 UTC (permalink / raw)
To: acme, jolsa
Cc: irogers, ak, rnsastry, linux-perf-users, maddy, james.clark,
kjain, namhyung, disgoel, linuxppc-dev
While parsing the tracepoint events in parse_events_add_tracepoint()
function, code checks for HAVE_LIBTRACEEVENT support. This is needed
since libtraceevent is necessary for tracepoint. But while adding
probe points, check for LIBTRACEEVENT is not done in case of perf probe.
Hence, in environment with missing libtraceevent-devel, it is
observed that adding a probe point shows below message though it
can't be used via perf record.
Example:
Adding probe point:
./perf probe 'vfs_getname=getname_flags:72 pathname=result->name:string'
Added new event:
probe:vfs_getname (on getname_flags:72 with pathname=result->name:string)
You can now use it in all perf tools, such as:
perf record -e probe:vfs_getname -aR sleep 1
But trying perf record:
./perf record -e probe:vfs_getname -aR sleep 1
event syntax error: 'probe:vfs_getname'
\___ unsupported tracepoint
libtraceevent is necessary for tracepoint support
Run 'perf list' for a list of valid events
The builtin tool like perf record needs libtraceevent to
parse tracefs. But still the probe can be used by enabling
via tracefs. Patch fixes the probe usage message to the user
based on presence of libtraceevent. With the fix,
# ./perf probe 'pmu:myprobe=schedule'
Added new event:
pmu:myprobe (on schedule)
perf is not linked with libtraceevent, to use the new probe you can use tracefs:
cd /sys/kernel/tracing/
echo 1 > events/pmu/myprobe/enable
echo 1 > tracing_on
cat trace_pipe
Before removing the probe, echo 0 > events/pmu/myprobe/enable
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
---
tools/perf/builtin-probe.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index ed73d0b89ca2..e72f6cea76f7 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -383,9 +383,18 @@ static int perf_add_probe_events(struct perf_probe_event *pevs, int npevs)
/* Note that it is possible to skip all events because of blacklist */
if (event) {
+#ifndef HAVE_LIBTRACEEVENT
+ pr_info("\nperf is not linked with libtraceevent, to use the new probe you can use tracefs:\n\n");
+ pr_info("\tcd /sys/kernel/tracing/\n");
+ pr_info("\techo 1 > events/%s/%s/enable\n", group, event);
+ pr_info("\techo 1 > tracing_on\n");
+ pr_info("\tcat trace_pipe\n");
+ pr_info("\tBefore removing the probe, echo 0 > events/%s/%s/enable\n", group, event);
+#else
/* Show how to use the event. */
pr_info("\nYou can now use it in all perf tools, such as:\n\n");
pr_info("\tperf record -e %s:%s -aR sleep 1\n\n", group, event);
+#endif
}
out_cleanup:
--
2.39.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] tools/perf: Fix usage of perf probe when libtraceevent is missing
2023-01-31 13:47 [PATCH] tools/perf: Fix usage of perf probe when libtraceevent is missing Athira Rajeev
@ 2023-02-02 0:50 ` Arnaldo Carvalho de Melo
2023-02-02 4:17 ` Athira Rajeev
0 siblings, 1 reply; 3+ messages in thread
From: Arnaldo Carvalho de Melo @ 2023-02-02 0:50 UTC (permalink / raw)
To: Athira Rajeev
Cc: irogers, ak, rnsastry, linux-perf-users, maddy, james.clark,
jolsa, kjain, namhyung, disgoel, linuxppc-dev
Em Tue, Jan 31, 2023 at 07:17:48PM +0530, Athira Rajeev escreveu:
> While parsing the tracepoint events in parse_events_add_tracepoint()
> function, code checks for HAVE_LIBTRACEEVENT support. This is needed
> since libtraceevent is necessary for tracepoint. But while adding
> probe points, check for LIBTRACEEVENT is not done in case of perf probe.
> Hence, in environment with missing libtraceevent-devel, it is
> observed that adding a probe point shows below message though it
> can't be used via perf record.
Thanks, applied.
- Arnaldo
> Example:
> Adding probe point:
> ./perf probe 'vfs_getname=getname_flags:72 pathname=result->name:string'
> Added new event:
> probe:vfs_getname (on getname_flags:72 with pathname=result->name:string)
>
> You can now use it in all perf tools, such as:
>
> perf record -e probe:vfs_getname -aR sleep 1
>
> But trying perf record:
> ./perf record -e probe:vfs_getname -aR sleep 1
> event syntax error: 'probe:vfs_getname'
> \___ unsupported tracepoint
> libtraceevent is necessary for tracepoint support
> Run 'perf list' for a list of valid events
>
> The builtin tool like perf record needs libtraceevent to
> parse tracefs. But still the probe can be used by enabling
> via tracefs. Patch fixes the probe usage message to the user
> based on presence of libtraceevent. With the fix,
>
> # ./perf probe 'pmu:myprobe=schedule'
> Added new event:
> pmu:myprobe (on schedule)
>
> perf is not linked with libtraceevent, to use the new probe you can use tracefs:
>
> cd /sys/kernel/tracing/
> echo 1 > events/pmu/myprobe/enable
> echo 1 > tracing_on
> cat trace_pipe
> Before removing the probe, echo 0 > events/pmu/myprobe/enable
>
> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
> ---
> tools/perf/builtin-probe.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
> index ed73d0b89ca2..e72f6cea76f7 100644
> --- a/tools/perf/builtin-probe.c
> +++ b/tools/perf/builtin-probe.c
> @@ -383,9 +383,18 @@ static int perf_add_probe_events(struct perf_probe_event *pevs, int npevs)
>
> /* Note that it is possible to skip all events because of blacklist */
> if (event) {
> +#ifndef HAVE_LIBTRACEEVENT
> + pr_info("\nperf is not linked with libtraceevent, to use the new probe you can use tracefs:\n\n");
> + pr_info("\tcd /sys/kernel/tracing/\n");
> + pr_info("\techo 1 > events/%s/%s/enable\n", group, event);
> + pr_info("\techo 1 > tracing_on\n");
> + pr_info("\tcat trace_pipe\n");
> + pr_info("\tBefore removing the probe, echo 0 > events/%s/%s/enable\n", group, event);
> +#else
> /* Show how to use the event. */
> pr_info("\nYou can now use it in all perf tools, such as:\n\n");
> pr_info("\tperf record -e %s:%s -aR sleep 1\n\n", group, event);
> +#endif
> }
>
> out_cleanup:
> --
> 2.39.0
>
--
- Arnaldo
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] tools/perf: Fix usage of perf probe when libtraceevent is missing
2023-02-02 0:50 ` Arnaldo Carvalho de Melo
@ 2023-02-02 4:17 ` Athira Rajeev
0 siblings, 0 replies; 3+ messages in thread
From: Athira Rajeev @ 2023-02-02 4:17 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo
Cc: Ian Rogers, Andi Kleen, rnsastry, linux-perf-users, maddy,
james.clark, Jiri Olsa, kjain, Namhyung Kim, disgoel,
linuxppc-dev
> On 02-Feb-2023, at 6:20 AM, Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
>
> Em Tue, Jan 31, 2023 at 07:17:48PM +0530, Athira Rajeev escreveu:
>> While parsing the tracepoint events in parse_events_add_tracepoint()
>> function, code checks for HAVE_LIBTRACEEVENT support. This is needed
>> since libtraceevent is necessary for tracepoint. But while adding
>> probe points, check for LIBTRACEEVENT is not done in case of perf probe.
>> Hence, in environment with missing libtraceevent-devel, it is
>> observed that adding a probe point shows below message though it
>> can't be used via perf record.
>
> Thanks, applied.
>
> - Arnaldo
Thanks Arnaldo
Athira
>
>
>> Example:
>> Adding probe point:
>> ./perf probe 'vfs_getname=getname_flags:72 pathname=result->name:string'
>> Added new event:
>> probe:vfs_getname (on getname_flags:72 with pathname=result->name:string)
>>
>> You can now use it in all perf tools, such as:
>>
>> perf record -e probe:vfs_getname -aR sleep 1
>>
>> But trying perf record:
>> ./perf record -e probe:vfs_getname -aR sleep 1
>> event syntax error: 'probe:vfs_getname'
>> \___ unsupported tracepoint
>> libtraceevent is necessary for tracepoint support
>> Run 'perf list' for a list of valid events
>>
>> The builtin tool like perf record needs libtraceevent to
>> parse tracefs. But still the probe can be used by enabling
>> via tracefs. Patch fixes the probe usage message to the user
>> based on presence of libtraceevent. With the fix,
>>
>> # ./perf probe 'pmu:myprobe=schedule'
>> Added new event:
>> pmu:myprobe (on schedule)
>>
>> perf is not linked with libtraceevent, to use the new probe you can use tracefs:
>>
>> cd /sys/kernel/tracing/
>> echo 1 > events/pmu/myprobe/enable
>> echo 1 > tracing_on
>> cat trace_pipe
>> Before removing the probe, echo 0 > events/pmu/myprobe/enable
>>
>> Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
>> ---
>> tools/perf/builtin-probe.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>>
>> diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
>> index ed73d0b89ca2..e72f6cea76f7 100644
>> --- a/tools/perf/builtin-probe.c
>> +++ b/tools/perf/builtin-probe.c
>> @@ -383,9 +383,18 @@ static int perf_add_probe_events(struct perf_probe_event *pevs, int npevs)
>>
>> /* Note that it is possible to skip all events because of blacklist */
>> if (event) {
>> +#ifndef HAVE_LIBTRACEEVENT
>> + pr_info("\nperf is not linked with libtraceevent, to use the new probe you can use tracefs:\n\n");
>> + pr_info("\tcd /sys/kernel/tracing/\n");
>> + pr_info("\techo 1 > events/%s/%s/enable\n", group, event);
>> + pr_info("\techo 1 > tracing_on\n");
>> + pr_info("\tcat trace_pipe\n");
>> + pr_info("\tBefore removing the probe, echo 0 > events/%s/%s/enable\n", group, event);
>> +#else
>> /* Show how to use the event. */
>> pr_info("\nYou can now use it in all perf tools, such as:\n\n");
>> pr_info("\tperf record -e %s:%s -aR sleep 1\n\n", group, event);
>> +#endif
>> }
>>
>> out_cleanup:
>> --
>> 2.39.0
>>
>
> --
>
> - Arnaldo
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-01-31 13:47 [PATCH] tools/perf: Fix usage of perf probe when libtraceevent is missing Athira Rajeev
2023-02-02 0:50 ` Arnaldo Carvalho de Melo
2023-02-02 4:17 ` Athira Rajeev
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