SF: Extract PresentLatencyTracker
Present fences will eventually be tracked per display to compute per-
display CompositorTiming, but for now extract a class and add tests.
Bug: 185535769
Test: libscheduler_test
Change-Id: Ifa7f27059dc0ca5c8ee4747dd2640fb9638fd2bc
diff --git a/services/surfaceflinger/Scheduler/Android.bp b/services/surfaceflinger/Scheduler/Android.bp
index 5de796d..5bd8a99 100644
--- a/services/surfaceflinger/Scheduler/Android.bp
+++ b/services/surfaceflinger/Scheduler/Android.bp
@@ -18,6 +18,7 @@
"libbase",
"libcutils",
"liblog",
+ "libui",
"libutils",
],
}
@@ -39,6 +40,7 @@
name: "libscheduler",
defaults: ["libscheduler_defaults"],
srcs: [
+ "src/PresentLatencyTracker.cpp",
"src/Timer.cpp",
],
local_include_dirs: ["include"],
@@ -50,6 +52,7 @@
test_suites: ["device-tests"],
defaults: ["libscheduler_defaults"],
srcs: [
+ "tests/PresentLatencyTrackerTest.cpp",
"tests/TimerTest.cpp",
],
static_libs: [
diff --git a/services/surfaceflinger/Scheduler/include/scheduler/PresentLatencyTracker.h b/services/surfaceflinger/Scheduler/include/scheduler/PresentLatencyTracker.h
new file mode 100644
index 0000000..23ae83f
--- /dev/null
+++ b/services/surfaceflinger/Scheduler/include/scheduler/PresentLatencyTracker.h
@@ -0,0 +1,54 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <memory>
+#include <queue>
+#include <utility>
+
+#include <scheduler/Time.h>
+
+namespace android {
+
+class FenceTime;
+
+namespace scheduler {
+
+// Computes composite-to-present latency by tracking recently composited frames pending to present.
+class PresentLatencyTracker {
+public:
+ // For tests.
+ static constexpr size_t kMaxPendingFrames = 4;
+
+ // Returns the present latency of the latest frame.
+ Duration trackPendingFrame(TimePoint compositeTime,
+ std::shared_ptr<FenceTime> presentFenceTime);
+
+private:
+ struct PendingFrame {
+ PendingFrame(TimePoint compositeTime, std::shared_ptr<FenceTime> presentFenceTime)
+ : compositeTime(compositeTime), presentFenceTime(std::move(presentFenceTime)) {}
+
+ const TimePoint compositeTime;
+ const std::shared_ptr<FenceTime> presentFenceTime;
+ };
+
+ std::queue<PendingFrame> mPendingFrames;
+};
+
+} // namespace scheduler
+} // namespace android
diff --git a/services/surfaceflinger/Scheduler/include/scheduler/Time.h b/services/surfaceflinger/Scheduler/include/scheduler/Time.h
index 6fa548e..2b3ad2d 100644
--- a/services/surfaceflinger/Scheduler/include/scheduler/Time.h
+++ b/services/surfaceflinger/Scheduler/include/scheduler/Time.h
@@ -32,13 +32,13 @@
struct Duration;
struct TimePoint : scheduler::SchedulerClock::time_point {
- explicit TimePoint(const Duration&);
+ explicit constexpr TimePoint(const Duration&);
// Implicit conversion from std::chrono counterpart.
constexpr TimePoint(scheduler::SchedulerClock::time_point p)
: scheduler::SchedulerClock::time_point(p) {}
- static TimePoint fromNs(nsecs_t);
+ static constexpr TimePoint fromNs(nsecs_t);
nsecs_t ns() const;
};
@@ -47,16 +47,16 @@
// Implicit conversion from std::chrono counterpart.
constexpr Duration(TimePoint::duration d) : TimePoint::duration(d) {}
- static Duration fromNs(nsecs_t ns) { return {std::chrono::nanoseconds(ns)}; }
+ static constexpr Duration fromNs(nsecs_t ns) { return {std::chrono::nanoseconds(ns)}; }
nsecs_t ns() const { return std::chrono::nanoseconds(*this).count(); }
};
using Period = Duration;
-inline TimePoint::TimePoint(const Duration& d) : scheduler::SchedulerClock::time_point(d) {}
+constexpr TimePoint::TimePoint(const Duration& d) : scheduler::SchedulerClock::time_point(d) {}
-inline TimePoint TimePoint::fromNs(nsecs_t ns) {
+constexpr TimePoint TimePoint::fromNs(nsecs_t ns) {
return TimePoint(Duration::fromNs(ns));
}
diff --git a/services/surfaceflinger/Scheduler/src/PresentLatencyTracker.cpp b/services/surfaceflinger/Scheduler/src/PresentLatencyTracker.cpp
new file mode 100644
index 0000000..8f3e081
--- /dev/null
+++ b/services/surfaceflinger/Scheduler/src/PresentLatencyTracker.cpp
@@ -0,0 +1,56 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <scheduler/PresentLatencyTracker.h>
+
+#include <cutils/compiler.h>
+#include <log/log.h>
+#include <ui/FenceTime.h>
+
+namespace android::scheduler {
+
+Duration PresentLatencyTracker::trackPendingFrame(TimePoint compositeTime,
+ std::shared_ptr<FenceTime> presentFenceTime) {
+ Duration presentLatency = Duration::zero();
+ while (!mPendingFrames.empty()) {
+ const auto& pendingFrame = mPendingFrames.front();
+ const auto presentTime =
+ TimePoint::fromNs(pendingFrame.presentFenceTime->getCachedSignalTime());
+
+ if (presentTime == TimePoint::fromNs(Fence::SIGNAL_TIME_PENDING)) {
+ break;
+ }
+
+ if (presentTime == TimePoint::fromNs(Fence::SIGNAL_TIME_INVALID)) {
+ ALOGE("%s: Invalid present fence", __func__);
+ } else {
+ presentLatency = presentTime - pendingFrame.compositeTime;
+ }
+
+ mPendingFrames.pop();
+ }
+
+ mPendingFrames.emplace(compositeTime, std::move(presentFenceTime));
+
+ if (CC_UNLIKELY(mPendingFrames.size() > kMaxPendingFrames)) {
+ ALOGE("%s: Too many pending frames", __func__);
+ mPendingFrames.pop();
+ }
+
+ return presentLatency;
+}
+
+} // namespace android::scheduler
diff --git a/services/surfaceflinger/Scheduler/tests/PresentLatencyTrackerTest.cpp b/services/surfaceflinger/Scheduler/tests/PresentLatencyTrackerTest.cpp
new file mode 100644
index 0000000..8952ca9
--- /dev/null
+++ b/services/surfaceflinger/Scheduler/tests/PresentLatencyTrackerTest.cpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include <algorithm>
+#include <array>
+
+#include <scheduler/PresentLatencyTracker.h>
+#include <ui/FenceTime.h>
+
+namespace android::scheduler {
+namespace {
+
+using FencePair = std::pair<sp<Fence>, std::shared_ptr<FenceTime>>;
+
+FencePair makePendingFence(FenceToFenceTimeMap& fenceMap) {
+ const auto fence = sp<Fence>::make();
+ return {fence, fenceMap.createFenceTimeForTest(fence)};
+}
+
+} // namespace
+
+TEST(PresentLatencyTrackerTest, skipsInvalidFences) {
+ PresentLatencyTracker tracker;
+
+ const TimePoint kCompositeTime = TimePoint::fromNs(999);
+ EXPECT_EQ(tracker.trackPendingFrame(kCompositeTime, FenceTime::NO_FENCE), Duration::zero());
+ EXPECT_EQ(tracker.trackPendingFrame(kCompositeTime, FenceTime::NO_FENCE), Duration::zero());
+ EXPECT_EQ(tracker.trackPendingFrame(kCompositeTime, FenceTime::NO_FENCE), Duration::zero());
+
+ FenceToFenceTimeMap fenceMap;
+ const auto [fence, fenceTime] = makePendingFence(fenceMap);
+ EXPECT_EQ(tracker.trackPendingFrame(kCompositeTime, fenceTime), Duration::zero());
+
+ fenceTime->signalForTest(9999);
+
+ EXPECT_EQ(tracker.trackPendingFrame(kCompositeTime, FenceTime::NO_FENCE),
+ Duration::fromNs(9000));
+}
+
+TEST(PresentLatencyTrackerTest, tracksPendingFrames) {
+ PresentLatencyTracker tracker;
+
+ FenceToFenceTimeMap fenceMap;
+ std::array<FencePair, PresentLatencyTracker::kMaxPendingFrames> fences;
+ std::generate(fences.begin(), fences.end(), [&fenceMap] { return makePendingFence(fenceMap); });
+
+ // The present latency is 0 if all fences are pending.
+ const TimePoint kCompositeTime = TimePoint::fromNs(1234);
+ for (const auto& [fence, fenceTime] : fences) {
+ EXPECT_EQ(tracker.trackPendingFrame(kCompositeTime, fenceTime), Duration::zero());
+ }
+
+ // If multiple frames have been presented...
+ constexpr size_t kPresentCount = fences.size() / 2;
+ for (size_t i = 0; i < kPresentCount; i++) {
+ fences[i].second->signalForTest(kCompositeTime.ns() + static_cast<nsecs_t>(i));
+ }
+
+ const auto fence = makePendingFence(fenceMap);
+
+ // ...then the present latency is measured using the latest frame.
+ constexpr Duration kPresentLatency = Duration::fromNs(static_cast<nsecs_t>(kPresentCount) - 1);
+ EXPECT_EQ(tracker.trackPendingFrame(kCompositeTime, fence.second), kPresentLatency);
+}
+
+} // namespace android::scheduler