From: Leo Yan <leo.yan@linaro.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@linaro.org>,
John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>,
linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Leo Yan <leo.yan@linaro.org>
Subject: [PATCH v1] perf cs-etm: Pass -1 as pid value for machine__set_current_tid()
Date: Sat, 13 Nov 2021 22:35:40 +0800 [thread overview]
Message-ID: <20211113143540.53957-1-leo.yan@linaro.org> (raw)
Currently, cs-etm passes the tid value for both tid and pid parameters
when calling machine__set_current_tid(), this can lead to confusion for
thread handling. E.g. we arbitrarily pass the same value for pid and
tid, perf tool will be misled to consider it is a main thread (see
thread__main_thread()).
On the other hand, Perf tool only can retrieve tid from Arm CoreSight
context packet, and we have no chance to know pid (it maps to kernel's
task_struct::tgid) from hardware tracing data. For this reason, this
patch passes -1 as pid for function machine__set_current_tid().
Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
tools/perf/util/cs-etm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index f323adb1af85..eed1a5930072 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1118,7 +1118,7 @@ int cs_etm__etmq_set_tid(struct cs_etm_queue *etmq,
if (cs_etm__get_cpu(trace_chan_id, &cpu) < 0)
return err;
- err = machine__set_current_tid(etm->machine, cpu, tid, tid);
+ err = machine__set_current_tid(etm->machine, cpu, -1, tid);
if (err)
return err;
--
2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Leo Yan <leo.yan@linaro.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>,
Namhyung Kim <namhyung@kernel.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@linaro.org>,
John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>,
linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Leo Yan <leo.yan@linaro.org>
Subject: [PATCH v1] perf cs-etm: Pass -1 as pid value for machine__set_current_tid()
Date: Sat, 13 Nov 2021 22:35:40 +0800 [thread overview]
Message-ID: <20211113143540.53957-1-leo.yan@linaro.org> (raw)
Currently, cs-etm passes the tid value for both tid and pid parameters
when calling machine__set_current_tid(), this can lead to confusion for
thread handling. E.g. we arbitrarily pass the same value for pid and
tid, perf tool will be misled to consider it is a main thread (see
thread__main_thread()).
On the other hand, Perf tool only can retrieve tid from Arm CoreSight
context packet, and we have no chance to know pid (it maps to kernel's
task_struct::tgid) from hardware tracing data. For this reason, this
patch passes -1 as pid for function machine__set_current_tid().
Signed-off-by: Leo Yan <leo.yan@linaro.org>
---
tools/perf/util/cs-etm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/cs-etm.c b/tools/perf/util/cs-etm.c
index f323adb1af85..eed1a5930072 100644
--- a/tools/perf/util/cs-etm.c
+++ b/tools/perf/util/cs-etm.c
@@ -1118,7 +1118,7 @@ int cs_etm__etmq_set_tid(struct cs_etm_queue *etmq,
if (cs_etm__get_cpu(trace_chan_id, &cpu) < 0)
return err;
- err = machine__set_current_tid(etm->machine, cpu, tid, tid);
+ err = machine__set_current_tid(etm->machine, cpu, -1, tid);
if (err)
return err;
--
2.25.1
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next reply other threads:[~2021-11-13 14:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-13 14:35 Leo Yan [this message]
2021-11-13 14:35 ` [PATCH v1] perf cs-etm: Pass -1 as pid value for machine__set_current_tid() Leo Yan
2021-11-18 17:14 ` Mathieu Poirier
2021-11-18 17:14 ` Mathieu Poirier
2021-11-19 0:33 ` Leo Yan
2021-11-19 0:33 ` Leo Yan
2021-11-23 3:14 ` Leo Yan
2021-11-23 3:14 ` Leo Yan
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