commit 0318ff0e9a747298cef19cea4678a554372909da
author Tim Murray <timmurray@google.com> Wed Jun 22 12:42:10 2016 -0700
committer The Android Automerger <android-build@google.com> Thu Jul 07 14:59:14 2016 -0700
tree 1ce2afe425a41a9d586393b11c11f962f3797ec0
parent 1d3090471e33bd709acf07cd661677658abbc9b5

surfaceflinger: make critical threads SCHED_FIFO

Sets the main thread, EventThread, and SFEventThread to SCHED_FIFO to
minimize jitter.

bug 24503801

Change-Id: I3751c00c79482842f5c0bdaec92b6cbfe62328a0

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index c541668..37b3757 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -462,6 +462,18 @@
         mSFEventThread = new EventThread(sfVsyncSrc, *this);
         mEventQueue.setEventThread(mSFEventThread);
 
+        // set EventThread and SFEventThread to SCHED_FIFO for minimum jitter
+        struct sched_param param = {0};
+        param.sched_priority = 1;
+        if (sched_setscheduler(mEventThread->getTid(), SCHED_FIFO, &param) != 0) {
+            ALOGE("Couldn't set SCHED_FIFO for EventThread");
+        }
+
+        if (sched_setscheduler(mSFEventThread->getTid(), SCHED_FIFO, &param) != 0) {
+            ALOGE("Couldn't set SCHED_FIFO for SFEventThread");
+        }
+
+
         // Get a RenderEngine for the given display / config (can't fail)
         mRenderEngine = RenderEngine::create(mEGLDisplay,
                 HAL_PIXEL_FORMAT_RGBA_8888);

services/surfaceflinger/SurfaceFlinger_hwc1.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
index d84d4e1..69fb8c5 100644
--- a/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
+++ b/services/surfaceflinger/SurfaceFlinger_hwc1.cpp
@@ -459,6 +459,18 @@
     mSFEventThread = new EventThread(sfVsyncSrc, *this);
     mEventQueue.setEventThread(mSFEventThread);
 
+    // set EventThread and SFEventThread to SCHED_FIFO for minimum jitter
+    struct sched_param param = {0};
+    param.sched_priority = 1;
+    if (sched_setscheduler(mEventThread->getTid(), SCHED_FIFO, &param) != 0) {
+        ALOGE("Couldn't set SCHED_FIFO for EventThread");
+    }
+
+    if (sched_setscheduler(mSFEventThread->getTid(), SCHED_FIFO, &param) != 0) {
+        ALOGE("Couldn't set SCHED_FIFO for SFEventThread");
+    }
+
+
     // Initialize the H/W composer object.  There may or may not be an
     // actual hardware composer underneath.
     mHwc = new HWComposer(this,

services/surfaceflinger/main_surfaceflinger.cpp

diff --git a/services/surfaceflinger/main_surfaceflinger.cpp b/services/surfaceflinger/main_surfaceflinger.cpp
index 97a1e8b..543d0c7 100644
--- a/services/surfaceflinger/main_surfaceflinger.cpp
+++ b/services/surfaceflinger/main_surfaceflinger.cpp
@@ -16,6 +16,8 @@
 
 #include <sys/resource.h>
 
+#include <sched.h>
+
 #include <cutils/sched_policy.h>
 #include <binder/IServiceManager.h>
 #include <binder/IPCThreadState.h>
@@ -61,6 +63,12 @@
     sp<GpuService> gpuservice = new GpuService();
     sm->addService(String16(GpuService::SERVICE_NAME), gpuservice, false);
 
+    struct sched_param param = {0};
+    param.sched_priority = 1;
+    if (sched_setscheduler(0, SCHED_FIFO, &param) != 0) {
+        ALOGE("Couldn't set SCHED_FIFO");
+    }
+
     // run surface flinger in this thread
     flinger->run();