[PATCH v1 2/2] perf bpf_counter: Fix handling of cpumap fixing hybrid

[Ian Rogers <irogers@google.com>]

Don't open evsels on all CPUs, open them just on the CPUs they
support. This avoids opening say an e-core event on a p-core and
getting a failure - achieve this by getting rid of the "all_cpu_map".

In install_pe functions don't use the cpu_map_idx as a CPU number,
translate the cpu_map_idx, which is a dense index into the cpu_map
skipping holes at the beginning, to a proper CPU number.

Before:
```
$ perf stat --bpf-counters -a -e cycles,instructions -- sleep 1

 Performance counter stats for 'system wide':

   <not supported>      cpu_atom/cycles/
       566,270,672      cpu_core/cycles/
   <not supported>      cpu_atom/instructions/
       572,792,836      cpu_core/instructions/           #    1.01  insn per cycle

       1.001595384 seconds time elapsed
```

After:
```
$ perf stat --bpf-counters -a -e cycles,instructions -- sleep 1

 Performance counter stats for 'system wide':

       443,299,201      cpu_atom/cycles/
     1,233,919,737      cpu_core/cycles/
       213,634,112      cpu_atom/instructions/           #    0.48  insn per cycle
     2,758,965,527      cpu_core/instructions/           #    2.24  insn per cycle

       1.001699485 seconds time elapsed
```

Fixes: 7fac83aaf2ee ("perf stat: Introduce 'bperf' to share hardware PMCs with BPF")
Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/bpf_counter.c        | 26 ++++++++++----------------
 tools/perf/util/bpf_counter_cgroup.c |  3 ++-
 2 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c
index 1c6cb5ea077e..ca5d01b9017d 100644
--- a/tools/perf/util/bpf_counter.c
+++ b/tools/perf/util/bpf_counter.c
@@ -336,6 +336,7 @@ static int bpf_program_profiler__install_pe(struct evsel *evsel, int cpu_map_idx
 {
 	struct bpf_prog_profiler_bpf *skel;
 	struct bpf_counter *counter;
+	int cpu = perf_cpu_map__cpu(evsel->core.cpus, cpu_map_idx).cpu;
 	int ret;
 
 	list_for_each_entry(counter, &evsel->bpf_counter_list, list) {
@@ -343,7 +344,7 @@ static int bpf_program_profiler__install_pe(struct evsel *evsel, int cpu_map_idx
 		assert(skel != NULL);
 
 		ret = bpf_map_update_elem(bpf_map__fd(skel->maps.events),
-					  &cpu_map_idx, &fd, BPF_ANY);
+					  &cpu, &fd, BPF_ANY);
 		if (ret)
 			return ret;
 	}
@@ -451,7 +452,6 @@ static int bperf_check_target(struct evsel *evsel,
 	return 0;
 }
 
-static	struct perf_cpu_map *all_cpu_map;
 static __u32 filter_entry_cnt;
 
 static int bperf_reload_leader_program(struct evsel *evsel, int attr_map_fd,
@@ -495,7 +495,7 @@ static int bperf_reload_leader_program(struct evsel *evsel, int attr_map_fd,
 	 * following evsel__open_per_cpu call
 	 */
 	evsel->leader_skel = skel;
-	evsel__open_per_cpu(evsel, all_cpu_map, -1);
+	evsel__open(evsel, evsel->core.cpus, evsel->core.threads);
 
 out:
 	bperf_leader_bpf__destroy(skel);
@@ -533,12 +533,6 @@ static int bperf__load(struct evsel *evsel, struct target *target)
 	if (bperf_check_target(evsel, target, &filter_type, &filter_entry_cnt))
 		return -1;
 
-	if (!all_cpu_map) {
-		all_cpu_map = perf_cpu_map__new_online_cpus();
-		if (!all_cpu_map)
-			return -1;
-	}
-
 	evsel->bperf_leader_prog_fd = -1;
 	evsel->bperf_leader_link_fd = -1;
 
@@ -656,9 +650,10 @@ static int bperf__load(struct evsel *evsel, struct target *target)
 static int bperf__install_pe(struct evsel *evsel, int cpu_map_idx, int fd)
 {
 	struct bperf_leader_bpf *skel = evsel->leader_skel;
+	int cpu = perf_cpu_map__cpu(evsel->core.cpus, cpu_map_idx).cpu;
 
 	return bpf_map_update_elem(bpf_map__fd(skel->maps.events),
-				   &cpu_map_idx, &fd, BPF_ANY);
+				   &cpu, &fd, BPF_ANY);
 }
 
 /*
@@ -667,13 +662,12 @@ static int bperf__install_pe(struct evsel *evsel, int cpu_map_idx, int fd)
  */
 static int bperf_sync_counters(struct evsel *evsel)
 {
-	int num_cpu, i, cpu;
+	struct perf_cpu cpu;
+	int idx;
+
+	perf_cpu_map__for_each_cpu(cpu, idx, evsel->core.cpus)
+		bperf_trigger_reading(evsel->bperf_leader_prog_fd, cpu.cpu);
 
-	num_cpu = perf_cpu_map__nr(all_cpu_map);
-	for (i = 0; i < num_cpu; i++) {
-		cpu = perf_cpu_map__cpu(all_cpu_map, i).cpu;
-		bperf_trigger_reading(evsel->bperf_leader_prog_fd, cpu);
-	}
 	return 0;
 }
 
diff --git a/tools/perf/util/bpf_counter_cgroup.c b/tools/perf/util/bpf_counter_cgroup.c
index ed6a29b106b4..690be3ce3e11 100644
--- a/tools/perf/util/bpf_counter_cgroup.c
+++ b/tools/perf/util/bpf_counter_cgroup.c
@@ -186,7 +186,8 @@ static int bperf_cgrp__load(struct evsel *evsel,
 }
 
 static int bperf_cgrp__install_pe(struct evsel *evsel __maybe_unused,
-				  int cpu __maybe_unused, int fd __maybe_unused)
+				  int cpu_map_idx __maybe_unused,
+				  int fd __maybe_unused)
 {
 	/* nothing to do */
 	return 0;
-- 
2.51.0.618.g983fd99d29-goog