[PATCH] perf record: Support sample-read topdown metric group for hybrid platforms

[zhengjun . xing]

From: Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx>

With the hardware TopDown metrics feature, the sample-read feature should
be supported for a TopDown group, e.g., sample a non-topdown event and read
a Topdown metric group. But the current perf record code errors are out.

For a TopDown metric group,the slots event must be the leader of the group,
but the leader slots event doesn't support sampling. To support sample-read
the TopDown metric group, uses the 2nd event of the group as the "leader"
for the purposes of sampling.

Only the platform with the TopDown metric feature supports sample-read the
topdown group. In commit acb65150a47c ("perf record: Support sample-read
topdown metric group"), it adds arch_topdown_sample_read() to indicate
whether the TopDown group supports sample-read, it should only work on the
non-hybrid systems, this patch extends the support for hybrid platforms.

Before:

 # ./perf record -e "{cpu_core/slots/,cpu_core/cycles/,cpu_core/topdown-retiring/}:S" -a sleep 1
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cpu_core/topdown-retiring/).
/bin/dmesg | grep -i perf may provide additional information.

After:

 # ./perf record -e "{cpu_core/slots/,cpu_core/cycles/,cpu_core/topdown-retiring/}:S" -a sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.238 MB perf.data (369 samples) ]

Fixes: acb65150a47c ("perf record: Support sample-read topdown metric group")
Signed-off-by: Zhengjun Xing <zhengjun.xing@xxxxxxxxxxxxxxx>
Reviewed-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
---
 tools/perf/arch/x86/util/evsel.c   |  3 ++-
 tools/perf/arch/x86/util/evsel.h   |  7 +++++++
 tools/perf/arch/x86/util/topdown.c | 21 ++++-----------------
 3 files changed, 13 insertions(+), 18 deletions(-)
 create mode 100644 tools/perf/arch/x86/util/evsel.h

diff --git a/tools/perf/arch/x86/util/evsel.c b/tools/perf/arch/x86/util/evsel.c
index ff4561b7b600..3501399cef35 100644
--- a/tools/perf/arch/x86/util/evsel.c
+++ b/tools/perf/arch/x86/util/evsel.c
@@ -5,6 +5,7 @@
 #include "util/env.h"
 #include "util/pmu.h"
 #include "linux/string.h"
+#include "evsel.h"
 
 void arch_evsel__set_sample_weight(struct evsel *evsel)
 {
@@ -32,7 +33,7 @@ void arch_evsel__fixup_new_cycles(struct perf_event_attr *attr)
 }
 
 /* Check whether the evsel's PMU supports the perf metrics */
-static bool evsel__sys_has_perf_metrics(const struct evsel *evsel)
+bool evsel__sys_has_perf_metrics(const struct evsel *evsel)
 {
 	const char *pmu_name = evsel->pmu_name ? evsel->pmu_name : "cpu";
 
diff --git a/tools/perf/arch/x86/util/evsel.h b/tools/perf/arch/x86/util/evsel.h
new file mode 100644
index 000000000000..19ad1691374d
--- /dev/null
+++ b/tools/perf/arch/x86/util/evsel.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _EVSEL_H
+#define _EVSEL_H 1
+
+bool evsel__sys_has_perf_metrics(const struct evsel *evsel);
+
+#endif
diff --git a/tools/perf/arch/x86/util/topdown.c b/tools/perf/arch/x86/util/topdown.c
index f4d5422e9960..f81a7cfe4d63 100644
--- a/tools/perf/arch/x86/util/topdown.c
+++ b/tools/perf/arch/x86/util/topdown.c
@@ -4,6 +4,7 @@
 #include "util/pmu.h"
 #include "util/topdown.h"
 #include "topdown.h"
+#include "evsel.h"
 
 /* Check whether there is a PMU which supports the perf metrics. */
 bool topdown_sys_has_perf_metrics(void)
@@ -55,33 +56,19 @@ void arch_topdown_group_warn(void)
 
 #define TOPDOWN_SLOTS		0x0400
 
-static bool is_topdown_slots_event(struct evsel *counter)
-{
-	if (!counter->pmu_name)
-		return false;
-
-	if (strcmp(counter->pmu_name, "cpu"))
-		return false;
-
-	if (counter->core.attr.config == TOPDOWN_SLOTS)
-		return true;
-
-	return false;
-}
-
 /*
  * Check whether a topdown group supports sample-read.
  *
- * Only Topdown metic supports sample-read. The slots
+ * Only Topdown metric supports sample-read. The slots
  * event must be the leader of the topdown group.
  */
 
 bool arch_topdown_sample_read(struct evsel *leader)
 {
-	if (!pmu_have_event("cpu", "slots"))
+	if (!evsel__sys_has_perf_metrics(leader))
 		return false;
 
-	if (is_topdown_slots_event(leader))
+	if (leader->core.attr.config == TOPDOWN_SLOTS)
 		return true;
 
 	return false;
-- 
2.25.1