2023-10-14 07:42:35

by Leo Yan

Subject: [PATCH v1 RESEND 1/2] perf cs-etm: Validate timestamp tracing in per-thread mode

So far, it's impossible to validate timestamp trace in Arm CoreSight when
the perf is in the per-thread mode. E.g. for the command:

perf record -e cs_etm/timestamp/ --per-thread -- ls

The command enables config 'timestamp' for 'cs_etm' event in the
per-thread mode. In this case, the function cs_etm_validate_config()
directly bails out and skips validation.

Given profiled process can be scheduled on any CPUs in the per-thread
mode, this patch validates timestamp tracing for all CPUs when detect
the CPU map is empty.

Signed-off-by: Leo Yan <[email protected]>
Reviewed-by: James Clark <[email protected]>
---
tools/perf/arch/arm/util/cs-etm.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index b8d6a953fd74..cf9ef9ba800b 100644
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -205,8 +205,17 @@ static int cs_etm_validate_config(struct auxtrace_record *itr,
for (i = 0; i < cpu__max_cpu().cpu; i++) {
struct perf_cpu cpu = { .cpu = i, };

- if (!perf_cpu_map__has(event_cpus, cpu) ||
- !perf_cpu_map__has(online_cpus, cpu))
+ /*
+ * In per-cpu case, do the validation for CPUs to work with.
+ * In per-thread case, the CPU map is empty. Since the traced
+ * program can run on any CPUs in this case, thus don't skip
+ * validation.
+ */
+ if (!perf_cpu_map__empty(event_cpus) &&
+ !perf_cpu_map__has(event_cpus, cpu))
+ continue;
+
+ if (!perf_cpu_map__has(online_cpus, cpu))
continue;

err = cs_etm_validate_context_id(itr, evsel, i);
--
2.34.1

2023-10-16 09:15:56

by Suzuki K Poulose

Subject: Re: [PATCH v1 RESEND 1/2] perf cs-etm: Validate timestamp tracing in per-thread mode

On 14/10/2023 08:41, Leo Yan wrote:
> So far, it's impossible to validate timestamp trace in Arm CoreSight when
> the perf is in the per-thread mode. E.g. for the command:
>
> perf record -e cs_etm/timestamp/ --per-thread -- ls
>
> The command enables config 'timestamp' for 'cs_etm' event in the
> per-thread mode. In this case, the function cs_etm_validate_config()
> directly bails out and skips validation.
>
> Given profiled process can be scheduled on any CPUs in the per-thread
> mode, this patch validates timestamp tracing for all CPUs when detect
> the CPU map is empty.
>
> Signed-off-by: Leo Yan <[email protected]>
> Reviewed-by: James Clark <[email protected]>

> ---
> tools/perf/arch/arm/util/cs-etm.c | 13 +++++++++++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
> index b8d6a953fd74..cf9ef9ba800b 100644
> --- a/tools/perf/arch/arm/util/cs-etm.c
> +++ b/tools/perf/arch/arm/util/cs-etm.c
> @@ -205,8 +205,17 @@ static int cs_etm_validate_config(struct auxtrace_record *itr,
> for (i = 0; i < cpu__max_cpu().cpu; i++) {
> struct perf_cpu cpu = { .cpu = i, };
>
> - if (!perf_cpu_map__has(event_cpus, cpu) ||
> - !perf_cpu_map__has(online_cpus, cpu))
> + /*
> + * In per-cpu case, do the validation for CPUs to work with.
> + * In per-thread case, the CPU map is empty. Since the traced
> + * program can run on any CPUs in this case, thus don't skip
> + * validation.
> + */
> + if (!perf_cpu_map__empty(event_cpus) &&
> + !perf_cpu_map__has(event_cpus, cpu))
> + continue;
> +
> + if (!perf_cpu_map__has(online_cpus, cpu))
> continue;
>

Acked-by: Suzuki K Poulose <[email protected]>