From 872679840aaf7338bf0ff4a49c069e841fda7204 Mon Sep 17 00:00:00 2001
From: rmorotti <romain.morotti@man.com>
Date: Thu, 21 Mar 2024 15:07:56 +0000
Subject: [PATCH] gh-117151: IO performance improvement, increase
 io.DEFAULT_BUFFER_SIZE to 128k, fix open() to use max(st_blksize,
 io.DEFAULT_BUFFER_SIZE)

---
 Lib/_pyio.py            | 6 +++---
 Modules/_io/_iomodule.h | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Lib/_pyio.py b/Lib/_pyio.py
index a3fede699218a15..7979d5766668917 100644
--- a/Lib/_pyio.py
+++ b/Lib/_pyio.py
@@ -23,8 +23,8 @@
     valid_seek_flags.add(os.SEEK_HOLE)
     valid_seek_flags.add(os.SEEK_DATA)
 
-# open() uses st_blksize whenever we can
-DEFAULT_BUFFER_SIZE = 8 * 1024  # bytes
+# open() uses max(st_blksize, io.DEFAULT_BUFFER_SIZE) when st_blksize is available
+DEFAULT_BUFFER_SIZE = 128 * 1024  # bytes
 
 # NOTE: Base classes defined here are registered with the "official" ABCs
 # defined in io.py. We don't use real inheritance though, because we don't want
@@ -249,7 +249,7 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
                 pass
             else:
                 if bs > 1:
-                    buffering = bs
+                    buffering = max(bs, DEFAULT_BUFFER_SIZE)
         if buffering < 0:
             raise ValueError("invalid buffering size")
         if buffering == 0:
diff --git a/Modules/_io/_iomodule.h b/Modules/_io/_iomodule.h
index afd638a120ba085..18cf20edf26f7d9 100644
--- a/Modules/_io/_iomodule.h
+++ b/Modules/_io/_iomodule.h
@@ -78,7 +78,7 @@ extern Py_ssize_t _PyIO_find_line_ending(
 */
 extern int _PyIO_trap_eintr(void);
 
-#define DEFAULT_BUFFER_SIZE (8 * 1024)  /* bytes */
+#define DEFAULT_BUFFER_SIZE (128 * 1024)  /* bytes */
 
 /*
  * Offset type for positioning.