- Add a general purpose resource allocator, vmem, from NetBSD. It was

   originally inspired by the Solaris vmem detailed in the proceedings
   of usenix 2001.  The NetBSD version was heavily refactored for bugs
   and simplicity.
 - Use this resource allocator to allocate the buffer and transient maps.
   Buffer cache defrags are reduced by 25% when used by filesystems with
   mixed block sizes.  Ultimately this may permit dynamic buffer cache
   sizing on low KVA machines.

Discussed with:	alc, kib, attilio
Tested by:	pho
Sponsored by:	EMC / Isilon Storage Division

1 files changed, 8 insertions, 15 deletions

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 767ed30..f6d5a85 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -64,6 +64,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/resourcevar.h>
 #include <sys/rwlock.h>
 #include <sys/sysctl.h>
+#include <sys/vmem.h>
 #include <sys/vmmeter.h>
 #include <sys/vnode.h>
 #include <geom/geom.h>
@@ -920,13 +921,13 @@ bfreekva(struct buf *bp)
 	atomic_subtract_long(&bufspace, bp->b_kvasize);
 	if ((bp->b_flags & B_UNMAPPED) == 0) {
 		BUF_CHECK_MAPPED(bp);
-		vm_map_remove(buffer_map, (vm_offset_t)bp->b_kvabase,
-		    (vm_offset_t)bp->b_kvabase + bp->b_kvasize);
+		vmem_free(buffer_arena, (vm_offset_t)bp->b_kvabase,
+		    bp->b_kvasize);
 	} else {
 		BUF_CHECK_UNMAPPED(bp);
 		if ((bp->b_flags & B_KVAALLOC) != 0) {
-			vm_map_remove(buffer_map, (vm_offset_t)bp->b_kvaalloc,
-			    (vm_offset_t)bp->b_kvaalloc + bp->b_kvasize);
+			vmem_free(buffer_arena, (vm_offset_t)bp->b_kvaalloc,
+			    bp->b_kvasize);
 		}
 		atomic_subtract_long(&unmapped_bufspace, bp->b_kvasize);
 		bp->b_flags &= ~(B_UNMAPPED | B_KVAALLOC);
@@ -2019,15 +2020,11 @@ static int
 allocbufkva(struct buf *bp, int maxsize, int gbflags)
 {
 	vm_offset_t addr;
-	int rv;
 
 	bfreekva(bp);
 	addr = 0;
 
-	vm_map_lock(buffer_map);
-	if (vm_map_findspace(buffer_map, vm_map_min(buffer_map), maxsize,
-	    &addr)) {
-		vm_map_unlock(buffer_map);
+	if (vmem_alloc(buffer_arena, maxsize, M_BESTFIT | M_NOWAIT, &addr)) {
 		/*
 		 * Buffer map is too fragmented.  Request the caller
 		 * to defragment the map.
@@ -2035,10 +2032,6 @@ allocbufkva(struct buf *bp, int maxsize, int gbflags)
 		atomic_add_int(&bufdefragcnt, 1);
 		return (1);
 	}
-	rv = vm_map_insert(buffer_map, NULL, 0, addr, addr + maxsize,
-	    VM_PROT_RW, VM_PROT_RW, MAP_NOFAULT);
-	KASSERT(rv == KERN_SUCCESS, ("vm_map_insert(buffer_map) rv %d", rv));
-	vm_map_unlock(buffer_map);
 	setbufkva(bp, addr, maxsize, gbflags);
 	atomic_add_long(&bufspace, bp->b_kvasize);
 	return (0);
@@ -2389,7 +2382,7 @@ restart:
  *	We block if:
  *		We have insufficient buffer headers
  *		We have insufficient buffer space
- *		buffer_map is too fragmented ( space reservation fails )
+ *		buffer_arena is too fragmented ( space reservation fails )
  *		If we have to flush dirty buffers ( but we try to avoid this )
  */
 static struct buf *
@@ -3593,7 +3586,7 @@ biodone(struct bio *bp)
 		done(bp);
 	if (transient) {
 		pmap_qremove(start, OFF_TO_IDX(end - start));
-		vm_map_remove(bio_transient_map, start, end);
+		vmem_free(transient_arena, start, end - start);
 		atomic_add_int(&inflight_transient_maps, -1);
 	}
 }