Don't fail when acpu_stats is non-monotonic.

This seems to happen very rarely. Submitting this client-side fix which
can be rolled back if we find a root cause.

Test: atest libadaptivecpu_test:KernelCpuFeatureReaderTest
Bug: 219960248
Change-Id: Ibbb54e94a7dbea42adf016bcbbc5f3d9fc63f9c9
Merged-In: Ibbb54e94a7dbea42adf016bcbbc5f3d9fc63f9c9
(cherry picked from commit a0d958ddbe4bff7150744d87ea7fa1c9fbf2db0a)

2 files changed, 16 insertions, 12 deletions

diff --git a/power-libperfmgr/adaptivecpu/KernelCpuFeatureReader.cpp b/power-libperfmgr/adaptivecpu/KernelCpuFeatureReader.cpp
index 794a16e..087f03d 100644
--- a/power-libperfmgr/adaptivecpu/KernelCpuFeatureReader.cpp
+++ b/power-libperfmgr/adaptivecpu/KernelCpuFeatureReader.cpp
@@ -58,10 +58,10 @@ bool KernelCpuFeatureReader::GetRecentCpuFeatures(
         // So, we only read the first CPU in each policy.
         const size_t statsIdx = CPU_POLICY_INDICES[i];
         if (stats[statsIdx].weighted_sum_freq < mPreviousStats[statsIdx].weighted_sum_freq) {
-            LOG(ERROR) << "New weighted_sum_freq is less than old: new="
-                       << stats[statsIdx].weighted_sum_freq
-                       << ", old=" << mPreviousStats[statsIdx].weighted_sum_freq;
-            return false;
+            LOG(WARNING) << "New weighted_sum_freq is less than old: new="
+                         << stats[statsIdx].weighted_sum_freq
+                         << ", old=" << mPreviousStats[statsIdx].weighted_sum_freq;
+            mPreviousStats[statsIdx].weighted_sum_freq = stats[statsIdx].weighted_sum_freq;
         }
         (*cpuPolicyAverageFrequencyHz)[i] =
                 static_cast<double>(stats[statsIdx].weighted_sum_freq -
@@ -70,10 +70,10 @@ bool KernelCpuFeatureReader::GetRecentCpuFeatures(
     }
     for (size_t i = 0; i < NUM_CPU_CORES; i++) {
         if (stats[i].total_idle_time_ns < mPreviousStats[i].total_idle_time_ns) {
-            LOG(ERROR) << "New total_idle_time_ns is less than old: new="
-                       << stats[i].total_idle_time_ns
-                       << ", old=" << mPreviousStats[i].total_idle_time_ns;
-            return false;
+            LOG(WARNING) << "New total_idle_time_ns is less than old: new="
+                         << stats[i].total_idle_time_ns
+                         << ", old=" << mPreviousStats[i].total_idle_time_ns;
+            mPreviousStats[i].total_idle_time_ns = stats[i].total_idle_time_ns;
         }
         (*cpuCoreIdleTimesPercentage)[i] =
                 static_cast<double>(stats[i].total_idle_time_ns -
diff --git a/power-libperfmgr/adaptivecpu/tests/KernelCpuFeatureReaderTest.cpp b/power-libperfmgr/adaptivecpu/tests/KernelCpuFeatureReaderTest.cpp
index f5cd51a..9e0ba03 100644
--- a/power-libperfmgr/adaptivecpu/tests/KernelCpuFeatureReaderTest.cpp
+++ b/power-libperfmgr/adaptivecpu/tests/KernelCpuFeatureReaderTest.cpp
@@ -107,7 +107,7 @@ TEST(KernelCpuFeatureReaderTest, noFile) {
     ASSERT_FALSE(reader.Init());
 }
 
-TEST(KernelCpuFeatureReaderTest, frequencies_negativeDiff) {
+TEST(KernelCpuFeatureReaderTest, frequencies_capsNegativeDiff) {
     std::unique_ptr<MockFilesystem> filesystem = std::make_unique<MockFilesystem>();
     std::unique_ptr<MockTimeSource> timeSource = std::make_unique<MockTimeSource>();
 
@@ -149,11 +149,13 @@ TEST(KernelCpuFeatureReaderTest, frequencies_negativeDiff) {
 
     std::array<double, NUM_CPU_POLICIES> cpuPolicyAverageFrequencyHz;
     std::array<double, NUM_CPU_CORES> cpuCoreIdleTimesPercentage;
-    ASSERT_FALSE(
+    ASSERT_TRUE(
             reader.GetRecentCpuFeatures(&cpuPolicyAverageFrequencyHz, &cpuCoreIdleTimesPercentage));
+    std::array<double, NUM_CPU_POLICIES> expectedFrequencies{{0}};
+    ASSERT_EQ(cpuPolicyAverageFrequencyHz, expectedFrequencies);
 }
 
-TEST(KernelCpuFeatureReaderTest, idleTimes_negativeDiff) {
+TEST(KernelCpuFeatureReaderTest, idleTimes_capsNegativeDiff) {
     std::unique_ptr<MockFilesystem> filesystem = std::make_unique<MockFilesystem>();
     std::unique_ptr<MockTimeSource> timeSource = std::make_unique<MockTimeSource>();
 
@@ -195,8 +197,10 @@ TEST(KernelCpuFeatureReaderTest, idleTimes_negativeDiff) {
 
     std::array<double, NUM_CPU_POLICIES> cpuPolicyAverageFrequencyHz;
     std::array<double, NUM_CPU_CORES> cpuCoreIdleTimesPercentage;
-    ASSERT_FALSE(
+    ASSERT_TRUE(
             reader.GetRecentCpuFeatures(&cpuPolicyAverageFrequencyHz, &cpuCoreIdleTimesPercentage));
+    std::array<double, NUM_CPU_CORES> expectedIdleTimes{{0}};
+    ASSERT_EQ(cpuCoreIdleTimesPercentage, expectedIdleTimes);
 }
 
 }  // namespace pixel