adbd: reduce queue depths.
Each operation we submit results in a contiguous allocation in the
kernel which can trigger OOM-killing. Tune the queue depths to reduce
the chances of this happening, with a minimal impact on performance.
Bug: http://b/126582877
Test: ./benchmark_device.py with blueline
Change-Id: I4b0f83d54a9a9a69f0ab48322d78fb137c94dd35
(cherry picked from commit baa7ce8f08477fa7e02080da7c51fbdc1c2f7a81)
diff --git a/daemon/usb.cpp b/daemon/usb.cpp
index 3b29ab5..1e37015 100644
--- a/daemon/usb.cpp
+++ b/daemon/usb.cpp
@@ -58,10 +58,12 @@
static std::optional<bool> gFfsAioSupported;
// Not all USB controllers support operations larger than 16k, so don't go above that.
-static constexpr size_t kUsbReadQueueDepth = 32;
+// Also, each submitted operation does an allocation in the kernel of that size, so we want to
+// minimize our queue depth while still maintaining a deep enough queue to keep the USB stack fed.
+static constexpr size_t kUsbReadQueueDepth = 8;
static constexpr size_t kUsbReadSize = 4 * PAGE_SIZE;
-static constexpr size_t kUsbWriteQueueDepth = 32;
+static constexpr size_t kUsbWriteQueueDepth = 8;
static constexpr size_t kUsbWriteSize = 4 * PAGE_SIZE;
static const char* to_string(enum usb_functionfs_event_type type) {