commit 4a322350b68f8998805032886642ce078066ef84
author Martin Liu <liumartin@google.com> Tue Mar 24 21:30:38 2020 +0800
committer Martin Liu <liumartin@google.com> Tue Mar 31 01:38:31 2020 +0800
tree f59b33e4840081d59027143a1c458e498ba0a3d7
parent 89260bd4176b50932b3a9baf91b325a401a8932e

SurfaceFlinger: align init and resume mode priority

Align init and resume mode RT priority. This could
also sync with HWC RT priority which reduces RT priority
inherit effort during HWbinder transaction.

Bug: 152294747
Test: check SF RT priority
Change-Id: I7c2f8d37de9e3a5ee403120c5a8d523b64c39a51

services/surfaceflinger/SurfaceFlinger.cpp

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 9c1c7f7..6ca1286 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -4131,6 +4131,9 @@
     }
 
     if (currentMode == HWC_POWER_MODE_OFF) {
+        if (SurfaceFlinger::setSchedFifo(true) != NO_ERROR) {
+            ALOGW("Couldn't set SCHED_FIFO on display on: %s\n", strerror(errno));
+        }
         getHwComposer().setPowerMode(*displayId, mode);
         if (display->isPrimary() && mode != HWC_POWER_MODE_DOZE_SUSPEND) {
             setVsyncEnabledInHWC(*displayId, mHWCVsyncPendingState);
@@ -4141,19 +4144,11 @@
         mVisibleRegionsDirty = true;
         mHasPoweredOff = true;
         repaintEverything();
-
-        struct sched_param param = {0};
-        param.sched_priority = 1;
-        if (sched_setscheduler(0, SCHED_FIFO, &param) != 0) {
-            ALOGW("Couldn't set SCHED_FIFO on display on");
-        }
     } else if (mode == HWC_POWER_MODE_OFF) {
         // Turn off the display
-        struct sched_param param = {0};
-        if (sched_setscheduler(0, SCHED_OTHER, &param) != 0) {
-            ALOGW("Couldn't set SCHED_OTHER on display off");
+        if (SurfaceFlinger::setSchedFifo(false) != NO_ERROR) {
+            ALOGW("Couldn't set SCHED_OTHER on display off: %s\n", strerror(errno));
         }
-
         if (display->isPrimary() && currentMode != HWC_POWER_MODE_DOZE_SUSPEND) {
             mScheduler->disableHardwareVsync(true);
             mScheduler->onScreenReleased(mAppConnectionHandle);
@@ -5340,6 +5335,26 @@
     }
 }
 
+status_t SurfaceFlinger::setSchedFifo(bool enabled) {
+    static constexpr int kFifoPriority = 2;
+    static constexpr int kOtherPriority = 0;
+
+    struct sched_param param = {0};
+    int sched_policy;
+    if (enabled) {
+        sched_policy = SCHED_FIFO;
+        param.sched_priority = kFifoPriority;
+    } else {
+        sched_policy = SCHED_OTHER;
+        param.sched_priority = kOtherPriority;
+    }
+
+    if (sched_setscheduler(0, sched_policy, &param) != 0) {
+        return -errno;
+    }
+    return NO_ERROR;
+}
+
 const sp<DisplayDevice> SurfaceFlinger::getDisplayByIdOrLayerStack(uint64_t displayOrLayerStack) {
     const sp<IBinder> displayToken = getPhysicalDisplayTokenLocked(DisplayId{displayOrLayerStack});
     if (displayToken) {

services/surfaceflinger/SurfaceFlinger.h

diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 6ab1fcf..60904f6 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -259,6 +259,9 @@
     // overhead that is caused by reading from sysprop.
     static bool useFrameRateApi;
 
+    // set main thread scheduling policy
+    static status_t setSchedFifo(bool enabled) ANDROID_API;
+
     static char const* getServiceName() ANDROID_API {
         return "SurfaceFlinger";
     }

services/surfaceflinger/main_surfaceflinger.cpp

diff --git a/services/surfaceflinger/main_surfaceflinger.cpp b/services/surfaceflinger/main_surfaceflinger.cpp
index d7ad9de..2b8424c 100644
--- a/services/surfaceflinger/main_surfaceflinger.cpp
+++ b/services/surfaceflinger/main_surfaceflinger.cpp
@@ -31,6 +31,7 @@
 #include <binder/ProcessState.h>
 #include <configstore/Utils.h>
 #include <displayservice/DisplayService.h>
+#include <errno.h>
 #include <hidl/LegacySupport.h>
 #include <processgroup/sched_policy.h>
 #include "SurfaceFlinger.h"
@@ -114,10 +115,8 @@
 
     startDisplayService(); // dependency on SF getting registered above
 
-    struct sched_param param = {0};
-    param.sched_priority = 2;
-    if (sched_setscheduler(0, SCHED_FIFO, &param) != 0) {
-        ALOGE("Couldn't set SCHED_FIFO");
+    if (SurfaceFlinger::setSchedFifo(true) != NO_ERROR) {
+        ALOGW("Couldn't set to SCHED_FIFO: %s", strerror(errno));
     }
 
     // run surface flinger in this thread