From b047ceca178996fec707b0820807e11edfbd8792 Mon Sep 17 00:00:00 2001
From: Jonas Konrad <me@yawk.at>
Date: Wed, 24 Jan 2024 16:39:01 +0100
Subject: [PATCH] Change default of iosqeAsyncThreshold to Integer.MAX_VALUE
 (#233)

---
 .../channel/uring/IOUringEventLoopGroup.java      |  6 +++---
 .../io/netty/incubator/channel/uring/Native.java  | 15 +++++++++++----
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/transport-classes-io_uring/src/main/java/io/netty/incubator/channel/uring/IOUringEventLoopGroup.java b/transport-classes-io_uring/src/main/java/io/netty/incubator/channel/uring/IOUringEventLoopGroup.java
index f0c86904..fbb2f21d 100644
--- a/transport-classes-io_uring/src/main/java/io/netty/incubator/channel/uring/IOUringEventLoopGroup.java
+++ b/transport-classes-io_uring/src/main/java/io/netty/incubator/channel/uring/IOUringEventLoopGroup.java
@@ -52,21 +52,21 @@ public IOUringEventLoopGroup(int nThreads) {
      * Create a new instance using the default number of threads and the given {@link ThreadFactory}.
      */
     public IOUringEventLoopGroup(ThreadFactory threadFactory) {
-        this(0, threadFactory, 0, Native.DEFAULT_IOSEQ_ASYNC_THRESHOLD);
+        this(0, threadFactory, 0, Native.DEFAULT_IOSQE_ASYNC_THRESHOLD);
     }
 
     /**
      * Create a new instance using the specified number of threads and the given {@link ThreadFactory}.
      */
     public IOUringEventLoopGroup(int nThreads, ThreadFactory threadFactory) {
-        this(nThreads, threadFactory, 0, Native.DEFAULT_IOSEQ_ASYNC_THRESHOLD);
+        this(nThreads, threadFactory, 0, Native.DEFAULT_IOSQE_ASYNC_THRESHOLD);
     }
 
     /**
      * Create a new instance using the specified number of threads and the given {@link Executor}.
      */
     public IOUringEventLoopGroup(int nThreads, Executor executor) {
-        this(nThreads, executor, 0, Native.DEFAULT_IOSEQ_ASYNC_THRESHOLD);
+        this(nThreads, executor, 0, Native.DEFAULT_IOSQE_ASYNC_THRESHOLD);
     }
 
     /**
diff --git a/transport-classes-io_uring/src/main/java/io/netty/incubator/channel/uring/Native.java b/transport-classes-io_uring/src/main/java/io/netty/incubator/channel/uring/Native.java
index 6b09b54c..a4ee381e 100644
--- a/transport-classes-io_uring/src/main/java/io/netty/incubator/channel/uring/Native.java
+++ b/transport-classes-io_uring/src/main/java/io/netty/incubator/channel/uring/Native.java
@@ -40,8 +40,15 @@
 final class Native {
     private static final InternalLogger logger = InternalLoggerFactory.getInstance(Native.class);
     static final int DEFAULT_RING_SIZE = Math.max(64, SystemPropertyUtil.getInt("io.netty.iouring.ringSize", 4096));
-    static final int DEFAULT_IOSEQ_ASYNC_THRESHOLD =
-            Math.max(0, SystemPropertyUtil.getInt("io.netty.iouring.iosqeAsyncThreshold", 25));
+    /**
+     * When there are more FDs (= connections) than this setting, the FDs will be marked as IOSQE_ASYNC, under the
+     * expectation that read/write ops on the FDs will usually block. If this expectation is correct, IOSQE_ASYNC can
+     * reduce CPU usage, but if the expectation is incorrect, it may add additional, unnecessary latency.
+     * <p>
+     * Default is to never use IOSQE_ASYNC.
+     */
+    static final int DEFAULT_IOSQE_ASYNC_THRESHOLD =
+            Math.max(0, SystemPropertyUtil.getInt("io.netty.iouring.iosqeAsyncThreshold", Integer.MAX_VALUE));
 
     static {
         Selector selector = null;
@@ -194,7 +201,7 @@ public void run() {
             (TCP_FASTOPEN_MODE & TFO_ENABLED_SERVER_MASK) == TFO_ENABLED_SERVER_MASK;
 
     static RingBuffer createRingBuffer(int ringSize) {
-        return createRingBuffer(ringSize, DEFAULT_IOSEQ_ASYNC_THRESHOLD);
+        return createRingBuffer(ringSize, DEFAULT_IOSQE_ASYNC_THRESHOLD);
     }
 
     static RingBuffer createRingBuffer(int ringSize, int iosqeAsyncThreshold) {
@@ -231,7 +238,7 @@ static RingBuffer createRingBuffer(int ringSize, int iosqeAsyncThreshold) {
     }
 
     static RingBuffer createRingBuffer() {
-        return createRingBuffer(DEFAULT_RING_SIZE, DEFAULT_IOSEQ_ASYNC_THRESHOLD);
+        return createRingBuffer(DEFAULT_RING_SIZE, DEFAULT_IOSQE_ASYNC_THRESHOLD);
     }
 
     static void checkAllIOSupported(int ringFd) {