Be more aggressive in using superpages in all mappings of objects:

- Add a new address space allocation method (VMFS_OPTIMAL_SPACE) for
  vm_map_find() that will try to alter the alignment of a mapping to match
  any existing superpage mappings of the object being mapped.  If no
  suitable address range is found with the necessary alignment,
  vm_map_find() will fall back to using the simple first-fit strategy
  (VMFS_ANY_SPACE).
- Change mmap() without MAP_FIXED, shmat(), and the GEM mapping ioctl to
  use VMFS_OPTIMAL_SPACE instead of VMFS_ANY_SPACE.

Reviewed by:	alc (earlier version)
MFC after:	2 weeks

3 files changed, 20 insertions, 8 deletions

diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index 778c054..9cf8827 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -1444,19 +1444,29 @@ vm_map_find(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
 	    vm_size_t length, int find_space, vm_prot_t prot,
 	    vm_prot_t max, int cow)
 {
-	vm_offset_t start;
+	vm_offset_t start, initial_addr;
 	int result;
 
-	start = *addr;
+	if (find_space == VMFS_OPTIMAL_SPACE && (object == NULL ||
+	    (object->flags & OBJ_COLORED) == 0))
+			find_space = VMFS_ANY_SPACE;
+	initial_addr = *addr;
+again:
+	start = initial_addr;
 	vm_map_lock(map);
 	do {
 		if (find_space != VMFS_NO_SPACE) {
 			if (vm_map_findspace(map, start, length, addr)) {
 				vm_map_unlock(map);
+				if (find_space == VMFS_OPTIMAL_SPACE) {
+					find_space = VMFS_ANY_SPACE;
+					goto again;
+				}
 				return (KERN_NO_SPACE);
 			}
 			switch (find_space) {
 			case VMFS_ALIGNED_SPACE:
+			case VMFS_OPTIMAL_SPACE:
 				pmap_align_superpage(object, offset, addr,
 				    length);
 				break;
@@ -1473,11 +1483,11 @@ vm_map_find(vm_map_t map, vm_object_t object, vm_ooffset_t offset,
 		}
 		result = vm_map_insert(map, object, offset, start, start +
 		    length, prot, max, cow);
-	} while (result == KERN_NO_SPACE && (find_space == VMFS_ALIGNED_SPACE
+	} while (result == KERN_NO_SPACE && (find_space == VMFS_ALIGNED_SPACE ||
 #ifdef VMFS_TLB_ALIGNED_SPACE
-	    || find_space == VMFS_TLB_ALIGNED_SPACE
+	    find_space == VMFS_TLB_ALIGNED_SPACE ||
 #endif
-	    ));
+	    find_space == VMFS_OPTIMAL_SPACE));
 	vm_map_unlock(map);
 	return (result);
 }
diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h
index a73691d..824a9a0 100644
--- a/sys/vm/vm_map.h
+++ b/sys/vm/vm_map.h
@@ -343,9 +343,10 @@ long vmspace_resident_count(struct vmspace *vmspace);
  */
 #define	VMFS_NO_SPACE		0	/* don't find; use the given range */
 #define	VMFS_ANY_SPACE		1	/* find a range with any alignment */
-#define	VMFS_ALIGNED_SPACE	2	/* find a superpage-aligned range */
+#define	VMFS_OPTIMAL_SPACE	2	/* find a range with optimal alignment*/
+#define	VMFS_ALIGNED_SPACE	3	/* find a superpage-aligned range */
 #if defined(__mips__)
-#define	VMFS_TLB_ALIGNED_SPACE	3	/* find a TLB entry aligned range */
+#define	VMFS_TLB_ALIGNED_SPACE	4	/* find a TLB entry aligned range */
 #endif
 
 /*
diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c
index c7e22c3..a5e6792 100644
--- a/sys/vm/vm_mmap.c
+++ b/sys/vm/vm_mmap.c
@@ -1603,7 +1603,8 @@ vm_mmap(vm_map_t map, vm_offset_t *addr, vm_size_t size, vm_prot_t prot,
 	else if (fitit)
 		rv = vm_map_find(map, object, foff, addr, size,
 		    object != NULL && object->type == OBJT_DEVICE ?
-		    VMFS_ALIGNED_SPACE : VMFS_ANY_SPACE, prot, maxprot, docow);
+		    VMFS_ALIGNED_SPACE : VMFS_OPTIMAL_SPACE, prot, maxprot,
+		    docow);
 	else
 		rv = vm_map_fixed(map, object, foff, *addr, size,
 				 prot, maxprot, docow);