commit d7599d832c96cc3ba0c2ad19653f29bdfe084284
author Alec Mouri <alecmouri@google.com> Wed May 22 19:58:00 2019 -0700
committer Alec Mouri <alecmouri@google.com> Wed Jun 19 16:46:09 2019 -0700
tree f351ab88d336ec32ee65ede7e80a7f2dda4515ea
parent b488afaa2addf5b101ef24d0e8fc9812cb3c7f26

[SurfaceFlinger] Add vsync offset information to systrace.

* Trace offset values in DispSyncSource
* Trace offset type in VSyncModulator
* Refactor how offsets are stored so that refresh rate type can be
encoded in VSyncModulator
* Add locking to catch a potential race condition when updating offsets,
as phase offsets can be accessed or updated on multiple threads.

Bug: 133325345
Test: verified that correct offsets are reported in systrace
Change-Id: I38d43b722cd54728a2e4de3df7dd472aceb1de15

services/surfaceflinger/Scheduler/DispSyncSource.cpp

diff --git a/services/surfaceflinger/Scheduler/DispSyncSource.cpp b/services/surfaceflinger/Scheduler/DispSyncSource.cpp
index 265b8aa..026b557 100644
--- a/services/surfaceflinger/Scheduler/DispSyncSource.cpp
+++ b/services/surfaceflinger/Scheduler/DispSyncSource.cpp
@@ -34,6 +34,8 @@
         mTraceVsync(traceVsync),
         mVsyncOnLabel(base::StringPrintf("VsyncOn-%s", name)),
         mVsyncEventLabel(base::StringPrintf("VSYNC-%s", name)),
+        mVsyncOffsetLabel(base::StringPrintf("VsyncOffset-%s", name)),
+        mVsyncNegativeOffsetLabel(base::StringPrintf("VsyncNegativeOffset-%s", name)),
         mDispSync(dispSync),
         mPhaseOffset(phaseOffset),
         mOffsetThresholdForNextVsync(offsetThresholdForNextVsync) {}
@@ -41,6 +43,7 @@
 void DispSyncSource::setVSyncEnabled(bool enable) {
     std::lock_guard lock(mVsyncMutex);
     if (enable) {
+        tracePhaseOffset();
         status_t err = mDispSync->addEventListener(mName, mPhaseOffset,
                                                    static_cast<DispSync::Callback*>(this),
                                                    mLastCallbackTime);
@@ -76,6 +79,7 @@
     const int numPeriods = phaseOffset / period;
     phaseOffset -= numPeriods * period;
     mPhaseOffset = phaseOffset;
+    tracePhaseOffset();
 
     // If we're not enabled, we don't need to mess with the listeners
     if (!mEnabled) {
@@ -94,11 +98,11 @@
     {
         std::lock_guard lock(mCallbackMutex);
         callback = mCallback;
+    }
 
-        if (mTraceVsync) {
-            mValue = (mValue + 1) % 2;
-            ATRACE_INT(mVsyncEventLabel.c_str(), mValue);
-        }
+    if (mTraceVsync) {
+        mValue = (mValue + 1) % 2;
+        ATRACE_INT(mVsyncEventLabel.c_str(), mValue);
     }
 
     if (callback != nullptr) {
@@ -106,4 +110,14 @@
     }
 }
 
-} // namespace android
\ No newline at end of file
+void DispSyncSource::tracePhaseOffset() {
+    if (mPhaseOffset > 0) {
+        ATRACE_INT(mVsyncOffsetLabel.c_str(), mPhaseOffset);
+        ATRACE_INT(mVsyncNegativeOffsetLabel.c_str(), 0);
+    } else {
+        ATRACE_INT(mVsyncOffsetLabel.c_str(), 0);
+        ATRACE_INT(mVsyncNegativeOffsetLabel.c_str(), -mPhaseOffset);
+    }
+}
+
+} // namespace android