This is a cleanup patch to Peter's new OBJT_PHYS VM object type

    and sysv shared memory support for it.  It implements a new
    PG_UNMANAGED flag that has slightly different characteristics
    from PG_FICTICIOUS.

    A new sysctl, kern.ipc.shm_use_phys has been added to enable the
    use of physically-backed sysv shared memory rather then swap-backed.
    Physically backed shm segments are not tracked with PV entries,
    allowing programs which use a large shm segment as a rendezvous
    point to operate without eating an insane amount of KVM in the
    PV entry management.  Read: Oracle.

    Peter's OBJT_PHYS object will also allow us to eventually implement
    page-table sharing and/or 4MB physical page support for such segments.
    We're half way there.

1 files changed, 9 insertions, 0 deletions

diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index e61be7f..a25c6ac 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -225,6 +225,13 @@ extern struct vpgqueues vm_page_queues[PQ_COUNT];
  * These are the flags defined for vm_page.
  *
  * Note: PG_FILLED and PG_DIRTY are added for the filesystems.
+ *
+ * Note: PG_UNMANAGED (used by OBJT_PHYS) indicates that the page is
+ * 	 not under PV management but otherwise should be treated as a
+ *	 normal page.  Pages not under PV management cannot be paged out
+ *	 via the object/vm_page_t because there is no knowledge of their
+ *	 pte mappings, nor can they be removed from their objects via 
+ *	 the object, and such pages are also not on any PQ queue.
  */
 #define	PG_BUSY		0x0001		/* page is in transit (O) */
 #define	PG_WANTED	0x0002		/* someone is waiting for page (O) */
@@ -236,6 +243,7 @@ extern struct vpgqueues vm_page_queues[PQ_COUNT];
 #define PG_CLEANCHK	0x0100		/* page will be checked for cleaning */
 #define PG_SWAPINPROG	0x0200		/* swap I/O in progress on page	     */
 #define PG_NOSYNC	0x0400		/* do not collect for syncer */
+#define PG_UNMANAGED	0x0800		/* No PV management for page */
 
 /*
  * Misc constants.
@@ -399,6 +407,7 @@ void vm_page_remove __P((vm_page_t));
 void vm_page_rename __P((vm_page_t, vm_object_t, vm_pindex_t));
 vm_offset_t vm_page_startup __P((vm_offset_t, vm_offset_t, vm_offset_t));
 vm_page_t vm_add_new_page __P((vm_offset_t pa));
+void vm_page_unmanage __P((vm_page_t));
 void vm_page_unwire __P((vm_page_t, int));
 void vm_page_wire __P((vm_page_t));
 void vm_page_unqueue __P((vm_page_t));