linux-kernel - [PATCH v3 11/27] perf pmu: Support 'cycles' and 'branches' inside hybrid PMU

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Date:   Mon, 29 Mar 2021 15:00:30 +0800
From:   Jin Yao <yao.jin@...ux.intel.com>
To:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com
Cc:     Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com,
        Jin Yao <yao.jin@...ux.intel.com>
Subject: [PATCH v3 11/27] perf pmu: Support 'cycles' and 'branches' inside hybrid PMU

On hybrid platform, user may want to enable the hardware event
only on one PMU. So following syntax is supported:

cpu_core/<hardware event>/
cpu_atom/<hardware event>/

  # perf stat -e cpu_core/cpu-cycles/ -a -- sleep 1

   Performance counter stats for 'system wide':

           6,049,336      cpu_core/cpu-cycles/

         1.003577042 seconds time elapsed

It enables the event 'cpu-cycles' only on cpu_core pmu.

But for 'cycles' and 'branches', the syntax doesn't work.

Before:

  # perf stat -e cpu_core/cycles/ -a -- sleep 1
  event syntax error: 'cpu_core/cycles/'
                                \___ unknown term 'cycles' for pmu 'cpu_core'

  # perf stat -e cpu_core/branches/ -a -- sleep 1
  event syntax error: 'cpu_core/branches/'
                                \___ unknown term 'branches' for pmu 'cpu_core'

For 'cpu-cycles', why it works is because the event is defined in
/sys/devices/cpu_core/events/. It's added as alias by
pmu_add_sys_aliases and it's treated as 'event' when parsing the
term->config.

We use a similar idea, create a pme_hybrid_fixup table for
'cycles' and 'branches' and add them as aliases.

After:

  # perf stat -e cpu_core/cycles/ -a -- sleep 1

   Performance counter stats for 'system wide':

           5,769,631      cpu_core/cycles/

         1.003833235 seconds time elapsed

  # perf stat -e cpu_core/branches/ -a -- sleep 1

   Performance counter stats for 'system wide':

             490,951      cpu_core/branches/

         1.003693946 seconds time elapsed

Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
---
v3:
 - New patch in v3.

 tools/perf/util/pmu.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index beff29981101..72e5ae5e868e 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -916,6 +916,35 @@ static int pmu_max_precise(const char *name)
 	return max_precise;
 }
 
+static void perf_pmu__add_hybrid_aliases(struct list_head *head)
+{
+	static struct pmu_event pme_hybrid_fixup[] = {
+		{
+			.name = "cycles",
+			.event = "event=0x3c",
+		},
+		{
+			.name = "branches",
+			.event = "event=0xc4",
+		},
+		{
+			.name = 0,
+			.event = 0,
+		},
+	};
+	int i = 0;
+
+	while (1) {
+		struct pmu_event *pe = &pme_hybrid_fixup[i++];
+
+		if (!pe->name)
+			break;
+
+		__perf_pmu__new_alias(head, NULL, (char *)pe->name, NULL,
+				      (char *)pe->event, NULL);
+	}
+}
+
 static struct perf_pmu *pmu_lookup(const char *name)
 {
 	struct perf_pmu *pmu;
@@ -955,6 +984,9 @@ static struct perf_pmu *pmu_lookup(const char *name)
 	pmu_add_cpu_aliases(&aliases, pmu);
 	pmu_add_sys_aliases(&aliases, pmu);
 
+	if (pmu->is_hybrid)
+		perf_pmu__add_hybrid_aliases(&aliases);
+
 	INIT_LIST_HEAD(&pmu->format);
 	INIT_LIST_HEAD(&pmu->aliases);
 	INIT_LIST_HEAD(&pmu->caps);
-- 
2.17.1