Use the HWC caching mechanism to avoid stalls in the ion driver.
HWC supports caching buffers for layers using "slot" assignments.
Use this in VrFlinger to avoid importing a buffer handle every
frame. The avoids periodic stalls we observe in the ion driver
when mapping a buffer into the HWC address space.
Bug: 66459419
Test: Observe systraces no longer have MapBuffer in HWC in steady
state; system does not drop frames.
Change-Id: Iba4161b33561322bfbccbfafe600b432a6fa7c44
diff --git a/libs/vr/libvrflinger/acquired_buffer.cpp b/libs/vr/libvrflinger/acquired_buffer.cpp
index fda9585..9614c6d 100644
--- a/libs/vr/libvrflinger/acquired_buffer.cpp
+++ b/libs/vr/libvrflinger/acquired_buffer.cpp
@@ -9,8 +9,8 @@
namespace dvr {
AcquiredBuffer::AcquiredBuffer(const std::shared_ptr<BufferConsumer>& buffer,
- LocalHandle acquire_fence)
- : buffer_(buffer), acquire_fence_(std::move(acquire_fence)) {}
+ LocalHandle acquire_fence, std::size_t slot)
+ : buffer_(buffer), acquire_fence_(std::move(acquire_fence)), slot_(slot) {}
AcquiredBuffer::AcquiredBuffer(const std::shared_ptr<BufferConsumer>& buffer,
int* error) {
@@ -31,18 +31,20 @@
}
}
-AcquiredBuffer::AcquiredBuffer(AcquiredBuffer&& other)
- : buffer_(std::move(other.buffer_)),
- acquire_fence_(std::move(other.acquire_fence_)) {}
+AcquiredBuffer::AcquiredBuffer(AcquiredBuffer&& other) {
+ *this = std::move(other);
+}
AcquiredBuffer::~AcquiredBuffer() { Release(LocalHandle(kEmptyFence)); }
AcquiredBuffer& AcquiredBuffer::operator=(AcquiredBuffer&& other) {
if (this != &other) {
- Release(LocalHandle(kEmptyFence));
+ Release();
- buffer_ = std::move(other.buffer_);
- acquire_fence_ = std::move(other.acquire_fence_);
+ using std::swap;
+ swap(buffer_, other.buffer_);
+ swap(acquire_fence_, other.acquire_fence_);
+ swap(slot_, other.slot_);
}
return *this;
}
@@ -81,8 +83,6 @@
ALOGD_IF(TRACE, "AcquiredBuffer::Release: buffer_id=%d release_fence=%d",
buffer_ ? buffer_->id() : -1, release_fence.Get());
if (buffer_) {
- // Close the release fence since we can't transfer it with an async release.
- release_fence.Close();
const int ret = buffer_->ReleaseAsync();
if (ret < 0) {
ALOGE("AcquiredBuffer::Release: Failed to release buffer %d: %s",
@@ -92,9 +92,10 @@
}
buffer_ = nullptr;
- acquire_fence_.Close();
}
+ acquire_fence_.Close();
+ slot_ = 0;
return 0;
}