--- Gnu-Mach/kern/slab.h	2020/09/02 04:45:20	1.1.1.1
+++ Gnu-Mach/kern/slab.h	2020/09/02 04:47:38	1.1.1.2
@@ -47,6 +47,7 @@
 #ifndef _KERN_SLAB_H
 #define _KERN_SLAB_H
 
+#include <cache.h>
 #include <kern/lock.h>
 #include <kern/list.h>
 #include <kern/rbtree.h>
@@ -147,14 +148,20 @@ typedef vm_offset_t (*kmem_slab_alloc_fn
 typedef void (*kmem_slab_free_fn_t)(vm_offset_t, vm_size_t);
 
 /*
- * Cache name buffer size.
+ * Cache name buffer size.  The size is chosen so that struct
+ * kmem_cache fits into two cache lines.  The size of a cache line on
+ * a typical CPU is 64 bytes.
  */
-#define KMEM_CACHE_NAME_SIZE 32
+#define KMEM_CACHE_NAME_SIZE 24
 
 /*
  * Cache of objects.
  *
  * Locking order : cpu_pool -> cache. CPU pools locking is ordered by CPU ID.
+ *
+ * Currently, SLAB_USE_CPU_POOLS is not defined.  KMEM_CACHE_NAME_SIZE
+ * is chosen so that the struct fits into two cache lines.  The first
+ * cache line contains all hot fields.
  */
 struct kmem_cache {
 #if SLAB_USE_CPU_POOLS
@@ -170,25 +177,27 @@ struct kmem_cache {
     struct list free_slabs;
     struct rbtree active_slabs;
     int flags;
+    size_t bufctl_dist; /* Distance from buffer to bufctl   */
+    size_t slab_size;
+    unsigned long bufs_per_slab;
+    unsigned long nr_objs;  /* Number of allocated objects */
+    unsigned long nr_free_slabs;
+    kmem_cache_ctor_t ctor;
+    /* All fields below are cold  */
     size_t obj_size;    /* User-provided size */
+    /* Assuming ! SLAB_USE_CPU_POOLS, here is the cacheline boundary */
     size_t align;
     size_t buf_size;    /* Aligned object size  */
-    size_t bufctl_dist; /* Distance from buffer to bufctl   */
-    size_t slab_size;
     size_t color;
     size_t color_max;
-    unsigned long bufs_per_slab;
-    unsigned long nr_objs;  /* Number of allocated objects */
     unsigned long nr_bufs;  /* Total number of buffers */
     unsigned long nr_slabs;
-    unsigned long nr_free_slabs;
-    kmem_cache_ctor_t ctor;
     kmem_slab_alloc_fn_t slab_alloc_fn;
     kmem_slab_free_fn_t slab_free_fn;
     char name[KMEM_CACHE_NAME_SIZE];
     size_t buftag_dist; /* Distance from buffer to buftag */
     size_t redzone_pad; /* Bytes from end of object to redzone word */
-};
+} __cacheline_aligned;
 
 /*
  * Mach-style declarations for struct kmem_cache.