adjust news and comments

Lib/_pyio.py

@@ -124,9 +124,7 @@ def open(file, mode="r", buffering=-1, encoding=None, errors=None,
     given, the default buffering policy works as follows:
 
    * Binary files are buffered in fixed-size chunks; the size of the buffer
-     is set to `max(io.DEFAULT_BUFFER_SIZE, st_blksize)` using a heuristic
-     trying to determine the underlying device's "block size" when available
-     and falling back on `io.DEFAULT_BUFFER_SIZE`.
+     is the maximum of the DEFAULT_BUFFER_SIZE and the device block size.
      On most systems, the buffer will typically be 131072 bytes long.
 
     * "Interactive" text files (files for which isatty() returns True)

Misc/NEWS.d/next/Library/2024-04-30-14-03-09.gh-issue-117151.yt2H8c.rst

@@ -1,5 +1,5 @@
 Increase ``io.DEFAULT_BUFFER_SIZE`` from 8k to 128k and adjust :func:`open` on
-platforms where ``fstat`` provides a ``st_blksize`` field (such as Linux) to use
-``max(io.DEFAULT_BUFFER_SIZE, device block size)`` rather than always using the
-device block size. This should improve I/O performance.
+platforms where :meth:`os.fstat` provides a ``st_blksize`` field (such as Linux)
+to use ``max(io.DEFAULT_BUFFER_SIZE, device block size)`` rather than always
+using the device block size. This should improve I/O performance.
 Patch by Romain Morotti.

Modules/_io/_iomodule.c

@@ -132,10 +132,8 @@ the size of a fixed-size chunk buffer.  When no buffering argument is
 given, the default buffering policy works as follows:
 
 * Binary files are buffered in fixed-size chunks; the size of the buffer
-  is set to `max(io.DEFAULT_BUFFER_SIZE, st_blksize)` using a heuristic
-  trying to determine the underlying device's "block size" when available
-  and falling back on `io.DEFAULT_BUFFER_SIZE`.
-  On most systems, the buffer will typically be 131072 bytes long.
+ is the maximum of the DEFAULT_BUFFER_SIZE and the device block size.
+ On most systems, the buffer will typically be 131072 bytes long.
 
 * "Interactive" text files (files for which isatty() returns True)
   use line buffering.  Other text files use the policy described above
@@ -201,7 +199,7 @@ static PyObject *
 _io_open_impl(PyObject *module, PyObject *file, const char *mode,
               int buffering, const char *encoding, const char *errors,
               const char *newline, int closefd, PyObject *opener)
-/*[clinic end generated code: output=aefafc4ce2b46dc0 input=bac1cd70f431fe9a]*/
+/*[clinic end generated code: output=aefafc4ce2b46dc0 input=105f6f1cb63368c4]*/
 {
     size_t i;