use 1 slot for all extended size classes

thestinger · thestinger · commit 8bfa1a7dd50e · 2021-05-01T22:10:20.000-04:00
This reduces memory usage and improves security in combination with the
guard slab feature.
diff --git a/README.md b/README.md
@@ -589,10 +589,10 @@ retaining the isolation.
 
 | size class | worst case internal fragmentation | slab slots | slab size | internal fragmentation for slabs |
 | - | - | - | - | - |
-| 20480 | 20.0% | 2 | 40960 | 0.0% |
-| 24576 | 16.66% | 2 | 49152 | 0.0% |
-| 28672 | 14.28% | 2 | 57344 | 0.0% |
-| 32768 | 12.5% | 2 | 65536 | 0.0% |
+| 20480 | 20.0% | 1 | 20480 | 0.0% |
+| 24576 | 16.66% | 1 | 24576 | 0.0% |
+| 28672 | 14.28% | 1 | 28672 | 0.0% |
+| 32768 | 12.5% | 1 | 32768 | 0.0% |
 | 40960 | 20.0% | 1 | 40960 | 0.0% |
 | 49152 | 16.66% | 1 | 49152 | 0.0% |
 | 57344 | 14.28% | 1 | 57344 | 0.0% |
diff --git a/h_malloc.c b/h_malloc.c
@@ -144,7 +144,7 @@ static const u16 size_class_slots[] = {
     /* 1024 */ 8, 8, 8, 8,
     /* 2048 */ 6, 5, 4, 4,
 #if CONFIG_EXTENDED_SIZE_CLASSES
-    /* 4096 */ 2, 2, 2, 2,
+    /* 4096 */ 1, 1, 1, 1,
     /* 8192 */ 1, 1, 1, 1,
     /* 16384 */ 1, 1, 1, 1,
 #endif
