round up list item counts to improve realloc performance

diff --git a/Objects/listobject.c b/Objects/listobject.c
index ecf46457d9ef1478ff3ecf028ff2b644ff21e9dd..f0eab0bb3bdc6e03b53a3efb7935e6bb1c594131 100644 (file)
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -33,6 +33,20 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #include <sys/types.h>         /* For size_t */
 #endif
 
+#define ROUNDUP(n, block) ((((n)+(block)-1)/(block))*(block))
+
+static int
+roundup(n)
+       int n;
+{
+       if (n < 500)
+               return ROUNDUP(n, 10);
+       else
+               return ROUNDUP(n, 100);
+}
+
+#define NRESIZE(var, type, nitems) RESIZE(var, type, roundup(nitems))
+
 object *
 newlistobject(size)
        int size;
@@ -135,7 +149,7 @@ ins1(self, where, v)
                return -1;
        }
        items = self->ob_item;
-       RESIZE(items, object *, self->ob_size+1);
+       NRESIZE(items, object *, self->ob_size+1);
        if (items == NULL) {
                err_nomem();
                return -1;
@@ -421,12 +435,12 @@ list_ass_slice(a, ilow, ihigh, v)
                        for (/*k = ihigh*/; k < a->ob_size; k++)
                                item[k+d] = item[k];
                        a->ob_size += d;
-                       RESIZE(item, object *, a->ob_size); /* Can't fail */
+                       NRESIZE(item, object *, a->ob_size); /* Can't fail */
                        a->ob_item = item;
                }
        }
        else { /* Insert d items; recycle ihigh-ilow items */
-               RESIZE(item, object *, a->ob_size + d);
+               NRESIZE(item, object *, a->ob_size + d);
                if (item == NULL) {
                        XDEL(recycle);
                        err_nomem();