svn commit: r262881 - projects/sendfile/sys/vm

[Gleb Smirnoff]

Author: glebius
Date: Fri Mar  7 01:13:48 2014
New Revision: 262881
URL: http://svnweb.freebsd.org/changeset/base/262881

Log:
  Add VM_ALLOC_NOWAIT flag, that tells vm_page_grab() to fail in case if
  it needs to sleep(9).
  
  Sponsored by:	Netflix
  Sponsored by:	Nginx, Inc.

Modified:
  projects/sendfile/sys/vm/vm_page.c
  projects/sendfile/sys/vm/vm_page.h

Modified: projects/sendfile/sys/vm/vm_page.c
==============================================================================
--- projects/sendfile/sys/vm/vm_page.c	Fri Mar  7 01:01:57 2014	(r262880)
+++ projects/sendfile/sys/vm/vm_page.c	Fri Mar  7 01:13:48 2014	(r262881)
@@ -2689,6 +2689,8 @@ retrylookup:
 		sleep = (allocflags & VM_ALLOC_IGN_SBUSY) != 0 ?
 		    vm_page_xbusied(m) : vm_page_busied(m);
 		if (sleep) {
+			if (allocflags & VM_ALLOC_NOWAIT)
+				return (NULL);
 			/*
 			 * Reference the page before unlocking and
 			 * sleeping so that the page daemon is less
@@ -2716,6 +2718,8 @@ retrylookup:
 	}
 	m = vm_page_alloc(object, pindex, allocflags & ~VM_ALLOC_IGN_SBUSY);
 	if (m == NULL) {
+		if (allocflags & VM_ALLOC_NOWAIT)
+			return (NULL);
 		VM_OBJECT_WUNLOCK(object);
 		VM_WAIT;
 		VM_OBJECT_WLOCK(object);

Modified: projects/sendfile/sys/vm/vm_page.h
==============================================================================
--- projects/sendfile/sys/vm/vm_page.h	Fri Mar  7 01:01:57 2014	(r262880)
+++ projects/sendfile/sys/vm/vm_page.h	Fri Mar  7 01:13:48 2014	(r262881)
@@ -390,6 +390,7 @@ vm_page_t PHYS_TO_VM_PAGE(vm_paddr_t pa)
 #define	VM_ALLOC_IGN_SBUSY	0x1000	/* vm_page_grab() only */
 #define	VM_ALLOC_NODUMP		0x2000	/* don't include in dump */
 #define	VM_ALLOC_SBUSY		0x4000	/* Shared busy the page */
+#define	VM_ALLOC_NOWAIT		0x8000	/* Return NULL instead of sleeping */
 
 #define	VM_ALLOC_COUNT_SHIFT	16
 #define	VM_ALLOC_COUNT(count)	((count) << VM_ALLOC_COUNT_SHIFT)