simpleperf: accept failures when getting hw counters on a cpu.

When built as a 32-bit program, simpleperf can't set sched_affinity
to a 64-bit only CPU. That can make simpleperf not be able to get
hardware counters on that CPU.

Bug: 243065368
Bug: 243479304
Test: run simpleperf_unit_test
Change-Id: I0eb2841e191e88a96eeae53ec95b265db194cfd8
(cherry picked from commit 5aded99e9925531836b0e2b511b1448b4d64785e)

2 files changed, 9 insertions, 7 deletions

diff --git a/simpleperf/cmd_stat.cpp b/simpleperf/cmd_stat.cpp
index f4df9b67..bd2cc5e3 100644
--- a/simpleperf/cmd_stat.cpp
+++ b/simpleperf/cmd_stat.cpp
@@ -433,7 +433,7 @@ class StatCommand : public Command {
  private:
   bool ParseOptions(const std::vector<std::string>& args,
                     std::vector<std::string>* non_option_args);
-  bool PrintHardwareCounters();
+  void PrintHardwareCounters();
   bool AddDefaultMeasuredEventTypes();
   void SetEventSelectionFlags();
   void MonitorEachThread();
@@ -480,7 +480,8 @@ bool StatCommand::Run(const std::vector<std::string>& args) {
     return false;
   }
   if (print_hw_counter_) {
-    return PrintHardwareCounters();
+    PrintHardwareCounters();
+    return true;
   }
   if (!app_package_name_.empty() && !in_app_context_) {
     if (!IsRoot()) {
@@ -793,16 +794,17 @@ std::optional<size_t> GetHardwareCountersOnCpu(int cpu) {
   return available_counters;
 }
 
-bool StatCommand::PrintHardwareCounters() {
+void StatCommand::PrintHardwareCounters() {
   for (int cpu : GetOnlineCpus()) {
     std::optional<size_t> counters = GetHardwareCountersOnCpu(cpu);
     if (!counters) {
-      LOG(ERROR) << "failed to get CPU PMU hardware counters on cpu " << cpu;
-      return false;
+      // When built as a 32-bit program, we can't set sched_affinity to a 64-bit only CPU. So we
+      // may not be able to get hardware counters on that CPU.
+      LOG(WARNING) << "Failed to get CPU PMU hardware counters on cpu " << cpu;
+      continue;
     }
     printf("There are %zu CPU PMU hardware counters available on cpu %d.\n", counters.value(), cpu);
   }
-  return true;
 }
 
 bool StatCommand::AddDefaultMeasuredEventTypes() {
diff --git a/simpleperf/workload.cpp b/simpleperf/workload.cpp
index 142ed713..92c6537b 100644
--- a/simpleperf/workload.cpp
+++ b/simpleperf/workload.cpp
@@ -167,7 +167,7 @@ bool Workload::SetCpuAffinity(int cpu) {
   CPU_ZERO(&mask);
   CPU_SET(cpu, &mask);
   if (sched_setaffinity(GetPid(), sizeof(mask), &mask) != 0) {
-    PLOG(ERROR) << "sched_setaffinity failed";
+    PLOG(WARNING) << "sched_setaffinity failed";
     return false;
   }
   return true;