svn commit: r254543 - in head/sys: kern vm

[Jeff Roberson]

Author: jeff
Date: Mon Aug 19 23:02:39 2013
New Revision: 254543
URL: http://svnweb.freebsd.org/changeset/base/254543

Log:
   - Use an arbitrary but reasonably large import size for kva on architectures
     that don't support superpages.  This keeps the number of spans and internal
     fragmentation lower.
   - When the user asks for alignment from vmem_xalloc adjust the imported size
     by 2*align to be certain we can satisfy the allocation.  This comes at
     the expense of potential failures when the backend can't supply enough
     memory but could supply the requested size and alignment.
  
  Sponsored by:	EMC / Isilon Storage Division

Modified:
  head/sys/kern/subr_vmem.c
  head/sys/vm/vm_init.c

Modified: head/sys/kern/subr_vmem.c
==============================================================================
--- head/sys/kern/subr_vmem.c	Mon Aug 19 22:25:36 2013	(r254542)
+++ head/sys/kern/subr_vmem.c	Mon Aug 19 23:02:39 2013	(r254543)
@@ -758,6 +758,7 @@ vmem_add1(vmem_t *vm, vmem_addr_t addr, 
 	bt_t *btfree;
 
 	MPASS(type == BT_TYPE_SPAN || type == BT_TYPE_SPAN_STATIC);
+	MPASS((size & vm->vm_quantum_mask) == 0);
 
 	btspan = bt_alloc(vm);
 	btspan->bt_type = type;
@@ -805,7 +806,7 @@ vmem_destroy1(vmem_t *vm)
 }
 
 static int
-vmem_import(vmem_t *vm, vmem_size_t size, int flags)
+vmem_import(vmem_t *vm, vmem_size_t size, vmem_size_t align, int flags)
 {
 	vmem_addr_t addr;
 	int error;
@@ -813,6 +814,12 @@ vmem_import(vmem_t *vm, vmem_size_t size
 	if (vm->vm_importfn == NULL)
 		return EINVAL;
 
+	/*
+	 * To make sure we get a span that meets the alignment we double it
+	 * and add the size to the tail.  This slightly overestimates.
+	 */
+	if (align != vm->vm_quantum_mask + 1)
+		size = (align * 2) + size;
 	size = roundup(size, vm->vm_import_quantum);
 
 	/*
@@ -1157,7 +1164,7 @@ vmem_xalloc(vmem_t *vm, const vmem_size_
 		 * imported region.  It is up to the user to specify the
 		 * import quantum such that it can satisfy any allocation.
 		 */
-		if (vmem_import(vm, size, flags) == 0)
+		if (vmem_import(vm, size, align, flags) == 0)
 			continue;
 
 		/*

Modified: head/sys/vm/vm_init.c
==============================================================================
--- head/sys/vm/vm_init.c	Mon Aug 19 22:25:36 2013	(r254542)
+++ head/sys/vm/vm_init.c	Mon Aug 19 23:02:39 2013	(r254543)
@@ -156,7 +156,8 @@ vm_mem_init(dummy)
 #if VM_NRESERVLEVEL > 0
 	    1 << (VM_LEVEL_0_ORDER + PAGE_SHIFT));
 #else
-	    PAGE_SIZE);
+	    /* On non-superpage architectures want large import sizes. */
+	    PAGE_SIZE * 1024);
 #endif
 
 	kmem_init_zero_region();