Camera: Bump the preview frame spacer thread priority
The preview frame spacer thread is part of the camera
critical path and any scheduling delays could contribute
to frame drops and poor UX.
Increase the respective thread priority to avoid potential
delays during buffer IPC.
Bug: 355665306
Flag: com.android.internal.camera.flags.bump_preview_frame_space_priority
Test: Camera CTS
Change-Id: Id9501f7132e8b534244ab4042e42387038177ab5
diff --git a/camera/camera_platform.aconfig b/camera/camera_platform.aconfig
index 121b9c4..1f67d2d 100644
--- a/camera/camera_platform.aconfig
+++ b/camera/camera_platform.aconfig
@@ -257,3 +257,13 @@
purpose: PURPOSE_BUGFIX
}
}
+
+flag {
+ namespace: "camera_platform"
+ name: "bump_preview_frame_space_priority"
+ description: "Increase the PreviewFrameSpacer thread priority"
+ bug: "355665306"
+ metadata {
+ purpose: PURPOSE_BUGFIX
+ }
+}
diff --git a/services/camera/libcameraservice/device3/PreviewFrameSpacer.cpp b/services/camera/libcameraservice/device3/PreviewFrameSpacer.cpp
index 83caa00..a04406e 100644
--- a/services/camera/libcameraservice/device3/PreviewFrameSpacer.cpp
+++ b/services/camera/libcameraservice/device3/PreviewFrameSpacer.cpp
@@ -18,10 +18,16 @@
#define ATRACE_TAG ATRACE_TAG_CAMERA
//#define LOG_NDEBUG 0
+#include <com_android_internal_camera_flags.h>
+
#include <utils/Log.h>
#include "PreviewFrameSpacer.h"
#include "Camera3OutputStream.h"
+#include "utils/SchedulingPolicyUtils.h"
+#include "utils/Utils.h"
+
+namespace flags = com::android::internal::camera::flags;
namespace android {
@@ -129,6 +135,24 @@
mLastCameraReadoutTime = bufferHolder.readoutTimestamp;
}
+status_t PreviewFrameSpacer::run(const char* name, int32_t priority, size_t stack) {
+ auto ret = Thread::run(name, priority, stack);
+ if (flags::bump_preview_frame_space_priority()) {
+ // Boost priority of the preview frame spacer thread to SCHED_FIFO.
+ pid_t previewFrameSpacerTid = getTid();
+ auto res = SchedulingPolicyUtils::requestPriorityDirect(getpid(), previewFrameSpacerTid,
+ RunThreadWithRealtimePriority::kRequestThreadPriority);
+ if (res != OK) {
+ ALOGW("Can't set realtime priority for preview frame spacer thread: %s (%d)",
+ strerror(-res), res);
+ } else {
+ ALOGV("Set real time priority for preview frame spacer thread (tid %d)",
+ previewFrameSpacerTid);
+ }
+ }
+ return ret;
+}
+
}; // namespace camera3
}; // namespace android
diff --git a/services/camera/libcameraservice/device3/PreviewFrameSpacer.h b/services/camera/libcameraservice/device3/PreviewFrameSpacer.h
index f46de3d..ab85189 100644
--- a/services/camera/libcameraservice/device3/PreviewFrameSpacer.h
+++ b/services/camera/libcameraservice/device3/PreviewFrameSpacer.h
@@ -58,6 +58,7 @@
bool threadLoop() override;
void requestExit() override;
+ status_t run(const char* name, int32_t priority = PRIORITY_DEFAULT, size_t stack = 0) override;
private:
// structure holding cached preview buffer info