Merge "libbinder - avoid pthread_cond_broadcast per call"

1 files changed, 8 insertions, 1 deletions

diff --git a/libs/binder/IPCThreadState.cpp b/libs/binder/IPCThreadState.cpp
index 2eee2c40a3..b038feb878 100644
--- a/libs/binder/IPCThreadState.cpp
+++ b/libs/binder/IPCThreadState.cpp
@@ -489,12 +489,14 @@ void IPCThreadState::flushCommands()
 void IPCThreadState::blockUntilThreadAvailable()
 {
     pthread_mutex_lock(&mProcess->mThreadCountLock);
+    mProcess->mWaitingForThreads++;
     while (mProcess->mExecutingThreadsCount >= mProcess->mMaxThreads) {
         ALOGW("Waiting for thread to be free. mExecutingThreadsCount=%lu mMaxThreads=%lu\n",
                 static_cast<unsigned long>(mProcess->mExecutingThreadsCount),
                 static_cast<unsigned long>(mProcess->mMaxThreads));
         pthread_cond_wait(&mProcess->mThreadCountDecrement, &mProcess->mThreadCountLock);
     }
+    mProcess->mWaitingForThreads--;
     pthread_mutex_unlock(&mProcess->mThreadCountLock);
 }
 
@@ -534,7 +536,12 @@ status_t IPCThreadState::getAndExecuteCommand()
             }
             mProcess->mStarvationStartTimeMs = 0;
         }
-        pthread_cond_broadcast(&mProcess->mThreadCountDecrement);
+
+        // Cond broadcast can be expensive, so don't send it every time a binder
+        // call is processed. b/168806193
+        if (mProcess->mWaitingForThreads > 0) {
+            pthread_cond_broadcast(&mProcess->mThreadCountDecrement);
+        }
         pthread_mutex_unlock(&mProcess->mThreadCountLock);
     }