From fe2dcb9453d6c7fbab0e32861c6bff65d77b172a Mon Sep 17 00:00:00 2001
From: jake <77554505+brxken128@users.noreply.github.com>
Date: Fri, 27 Jan 2023 12:50:55 +0000
Subject: [PATCH] io: increase `MAX_BUF` from 16384 to 2MiB (#5397)

---
 tokio/src/fs/file/tests.rs   | 8 ++++----
 tokio/src/io/blocking.rs     | 2 +-
 tokio/src/io/stdio_common.rs | 3 +--
 3 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/tokio/src/fs/file/tests.rs b/tokio/src/fs/file/tests.rs
index 1c90a8d1541..7c61b3c4b31 100644
--- a/tokio/src/fs/file/tests.rs
+++ b/tokio/src/fs/file/tests.rs
@@ -231,12 +231,12 @@ fn flush_while_idle() {
 #[cfg_attr(miri, ignore)] // takes a really long time with miri
 fn read_with_buffer_larger_than_max() {
     // Chunks
-    let chunk_a = 16 * 1024;
+    let chunk_a = crate::io::blocking::MAX_BUF;
     let chunk_b = chunk_a * 2;
     let chunk_c = chunk_a * 3;
     let chunk_d = chunk_a * 4;
 
-    assert_eq!(chunk_d / 1024, 64);
+    assert_eq!(chunk_d / 1024 / 1024, 8);
 
     let mut data = vec![];
     for i in 0..(chunk_d - 1) {
@@ -303,12 +303,12 @@ fn read_with_buffer_larger_than_max() {
 #[cfg_attr(miri, ignore)] // takes a really long time with miri
 fn write_with_buffer_larger_than_max() {
     // Chunks
-    let chunk_a = 16 * 1024;
+    let chunk_a = crate::io::blocking::MAX_BUF;
     let chunk_b = chunk_a * 2;
     let chunk_c = chunk_a * 3;
     let chunk_d = chunk_a * 4;
 
-    assert_eq!(chunk_d / 1024, 64);
+    assert_eq!(chunk_d / 1024 / 1024, 8);
 
     let mut data = vec![];
     for i in 0..(chunk_d - 1) {
diff --git a/tokio/src/io/blocking.rs b/tokio/src/io/blocking.rs
index f6db4500af1..416573e9732 100644
--- a/tokio/src/io/blocking.rs
+++ b/tokio/src/io/blocking.rs
@@ -26,7 +26,7 @@ pub(crate) struct Buf {
     pos: usize,
 }
 
-pub(crate) const MAX_BUF: usize = 16 * 1024;
+pub(crate) const MAX_BUF: usize = 2 * 1024 * 1024;
 
 #[derive(Debug)]
 enum State<T> {
diff --git a/tokio/src/io/stdio_common.rs b/tokio/src/io/stdio_common.rs
index 2715ba7923a..b1cc61d7ac4 100644
--- a/tokio/src/io/stdio_common.rs
+++ b/tokio/src/io/stdio_common.rs
@@ -108,14 +108,13 @@ where
 #[cfg(test)]
 #[cfg(not(loom))]
 mod tests {
+    use crate::io::blocking::MAX_BUF;
     use crate::io::AsyncWriteExt;
     use std::io;
     use std::pin::Pin;
     use std::task::Context;
     use std::task::Poll;
 
-    const MAX_BUF: usize = 16 * 1024;
-
     struct TextMockWriter;
 
     impl crate::io::AsyncWrite for TextMockWriter {