commit d0afeb7ccc3f90db83fe7369a9598c0b0960e024
author Pascal Mütschard <pmuetschard@google.com> Wed Mar 13 12:08:26 2024 +0100
committer Pascal Mütschard <pmuetschard@google.com> Tue Apr 23 10:32:59 2024 +0200
tree 8f4df5b97e8efbfb7bb34e2df12f7402a094817f
parent 3e48aa434d0c6a5813ea7e8e2b7b547deb1c9a36

Improvements to SF's BackgroundExcecutor.

- stop using utils/Singleton.h (it's marked as DO NOT USE)
- add a low priority instance
- explicitly set the thread priorities for both the HP and LP instances.

Test: manual, libsurfaceflinger_unittest
Bug: http://b/336461947
Change-Id: Ie10f663ed43aad21ba2a5235cd86a1101dec0cd7

services/surfaceflinger/BackgroundExecutor.cpp

diff --git a/services/surfaceflinger/BackgroundExecutor.cpp b/services/surfaceflinger/BackgroundExecutor.cpp
index 5a1ec6f..3cef875 100644
--- a/services/surfaceflinger/BackgroundExecutor.cpp
+++ b/services/surfaceflinger/BackgroundExecutor.cpp
@@ -19,6 +19,9 @@
 #define LOG_TAG "BackgroundExecutor"
 #define ATRACE_TAG ATRACE_TAG_GRAPHICS
 
+#include <processgroup/sched_policy.h>
+#include <pthread.h>
+#include <sched.h>
 #include <utils/Log.h>
 #include <mutex>
 
@@ -26,14 +29,24 @@
 
 namespace android {
 
-ANDROID_SINGLETON_STATIC_INSTANCE(BackgroundExecutor);
+namespace {
 
-BackgroundExecutor::BackgroundExecutor() : Singleton<BackgroundExecutor>() {
+void set_thread_priority(bool highPriority) {
+    set_sched_policy(0, highPriority ? SP_FOREGROUND : SP_BACKGROUND);
+    struct sched_param param = {0};
+    param.sched_priority = highPriority ? 2 : 0 /* must be 0 for non-RT */;
+    sched_setscheduler(gettid(), highPriority ? SCHED_FIFO : SCHED_NORMAL, &param);
+}
+
+} // anonymous namespace
+
+BackgroundExecutor::BackgroundExecutor(bool highPriority) {
     // mSemaphore must be initialized before any calls to
     // BackgroundExecutor::sendCallbacks. For this reason, we initialize it
     // within the constructor instead of within mThread.
     LOG_ALWAYS_FATAL_IF(sem_init(&mSemaphore, 0, 0), "sem_init failed");
-    mThread = std::thread([&]() {
+    mThread = std::thread([&, highPriority]() {
+        set_thread_priority(highPriority);
         while (!mDone) {
             LOG_ALWAYS_FATAL_IF(sem_wait(&mSemaphore), "sem_wait failed (%d)", errno);
             auto callbacks = mCallbacksQueue.pop();
@@ -45,6 +58,11 @@
             }
         }
     });
+    if (highPriority) {
+        pthread_setname_np(mThread.native_handle(), "BckgrndExec HP");
+    } else {
+        pthread_setname_np(mThread.native_handle(), "BckgrndExec LP");
+    }
 }
 
 BackgroundExecutor::~BackgroundExecutor() {