From b99348e5ea4da3e6070eb2eb8c14b6e007101041 Mon Sep 17 00:00:00 2001
From: Alan Cox <alc@FreeBSD.org>
Date: Fri, 9 Jul 2010 19:38:30 +0000
Subject: [PATCH] Add support for the VM_ALLOC_COUNT() hint to vm_page_alloc().
  Consequently, the maintenance of vm_pageout_deficit can be localized to just
 two places: vm_page_alloc() and vm_pageout_scan().

This change also corrects an off-by-one error in the maintenance of
vm_pageout_deficit.  Historically, the buffer cache functions, allocbuf()
and vm_hold_load_pages(), have not taken into account that vm_page_alloc()
already increments vm_pageout_deficit by one.

Reviewed by:	kib
---
 sys/kern/vfs_bio.c | 5 ++---
 sys/vm/vm_page.c   | 9 +++------
 sys/vm/vm_page.h   | 1 -
 3 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 762b2538acdd..9d2beba89ae2 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -3752,10 +3752,9 @@ vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to)
 		 * process we are.
 		 */
 		p = vm_page_alloc(NULL, pg >> PAGE_SHIFT, VM_ALLOC_NOOBJ |
-		    VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
+		    VM_ALLOC_SYSTEM | VM_ALLOC_WIRED |
+		    VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT));
 		if (!p) {
-			atomic_add_int(&vm_pageout_deficit,
-			    (to - pg) >> PAGE_SHIFT);
 			VM_WAIT;
 			goto tryagain;
 		}
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c
index 61718f4b9301..348ab99403e0 100644
--- a/sys/vm/vm_page.c
+++ b/sys/vm/vm_page.c
@@ -1264,7 +1264,8 @@ vm_page_alloc(vm_object_t object, vm_pindex_t pindex, int req)
 		 * Not allocatable, give up.
 		 */
 		mtx_unlock(&vm_page_queue_free_mtx);
-		atomic_add_int(&vm_pageout_deficit, 1);
+		atomic_add_int(&vm_pageout_deficit,
+		    MAX((u_int)req >> VM_ALLOC_COUNT_SHIFT, 1));
 		pagedaemon_wakeup();
 		return (NULL);
 	}
@@ -2041,7 +2042,6 @@ vm_page_t
 vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags)
 {
 	vm_page_t m;
-	u_int count;
 
 	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
 	KASSERT((allocflags & VM_ALLOC_RETRY) != 0,
@@ -2071,12 +2071,9 @@ vm_page_grab(vm_object_t object, vm_pindex_t pindex, int allocflags)
 		}
 	}
 	m = vm_page_alloc(object, pindex, allocflags & ~(VM_ALLOC_RETRY |
-	    VM_ALLOC_IGN_SBUSY | VM_ALLOC_COUNT_MASK));
+	    VM_ALLOC_IGN_SBUSY));
 	if (m == NULL) {
 		VM_OBJECT_UNLOCK(object);
-		count = (u_int)allocflags >> VM_ALLOC_COUNT_SHIFT;
-		if (count > 0)
-			atomic_add_int(&vm_pageout_deficit, count);
 		VM_WAIT;
 		VM_OBJECT_LOCK(object);
 		goto retrylookup;
diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index 62868cd80f88..a877c43c0906 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -321,7 +321,6 @@ extern struct vpglocks vm_page_queue_lock;
 
 #define	VM_ALLOC_COUNT_SHIFT	16
 #define	VM_ALLOC_COUNT(count)	((count) << VM_ALLOC_COUNT_SHIFT)
-#define	VM_ALLOC_COUNT_MASK	VM_ALLOC_COUNT(0xffff)
 
 void vm_page_flag_set(vm_page_t m, unsigned short bits);
 void vm_page_flag_clear(vm_page_t m, unsigned short bits);