Speed up reading of small files. This avoids multiple C read() calls on pyc files.
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 34ff1e0..df3affe 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -572,6 +572,7 @@
#endif
)
{
+ size_t addend;
#ifdef HAVE_FSTAT
if (end != (Py_off_t)-1) {
/* Files claiming a size smaller than SMALLCHUNK may
@@ -589,9 +590,16 @@
}
#endif
/* Expand the buffer by an amount proportional to the current size,
- giving us amortized linear-time behavior. Use a less-than-double
- growth factor to avoid excessive allocation. */
- return currentsize + (currentsize >> 3) + 6;
+ giving us amortized linear-time behavior. For bigger sizes, use a
+ less-than-double growth factor to avoid excessive allocation. */
+ if (currentsize > 65536)
+ addend = currentsize >> 3;
+ else
+ addend = 256 + currentsize;
+ if (addend < SMALLCHUNK)
+ /* Avoid tiny read() calls. */
+ addend = SMALLCHUNK;
+ return addend + currentsize;
}
static PyObject *