Add a "NO_SWAPPING" option to disable swapping. This was originally done

to help diagnose a problem on wcarchive (where the kernel stack was
sometimes not present), but is useful in its own right since swapping
actually reduces performance on some systems (such as wcarchive).
Note: swapping in this context means making the U pages pageable and has
nothing to do with generic VM paging, which is unaffected by this option.

Reviewed by:	 <dyson>

2 files changed, 24 insertions, 15 deletions

diff --git a/sys/vm/vm_glue.c b/sys/vm/vm_glue.c
index 22bda4f..1d45e37 100644
--- a/sys/vm/vm_glue.c
+++ b/sys/vm/vm_glue.c
@@ -59,7 +59,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_glue.c,v 1.37 1996/01/25 07:15:40 phk Exp $
+ * $Id: vm_glue.c,v 1.38 1996/01/29 12:10:30 davidg Exp $
  */
 
 #include "opt_sysvipc.h"
@@ -484,12 +484,12 @@ loop:
 	goto loop;
 }
 
+#ifndef NO_SWAPPING
+
 #define	swappable(p) \
 	(((p)->p_lock == 0) && \
 		((p)->p_flag & (P_TRACED|P_NOSWAP|P_SYSTEM|P_INMEM|P_WEXIT|P_PHYSIO|P_SWAPPING)) == P_INMEM)
 
-extern int vm_pageout_free_min;
-
 /*
  * Swapout is driven by the pageout daemon.  Very simple, we find eligible
  * procs and unwire their u-areas.  We try to always "swap" at least one
@@ -600,6 +600,7 @@ swapout(p)
 	p->p_flag &= ~P_SWAPPING;
 	p->p_swtime = 0;
 }
+#endif /* !NO_SWAPPING */
 
 #ifdef DDB
 /*
diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c
index 3ba895c..7e92337 100644
--- a/sys/vm/vm_pageout.c
+++ b/sys/vm/vm_pageout.c
@@ -65,7 +65,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_pageout.c,v 1.64 1996/01/19 04:00:23 dyson Exp $
+ * $Id: vm_pageout.c,v 1.65 1996/01/31 12:44:33 davidg Exp $
  */
 
 /*
@@ -113,6 +113,7 @@ static struct kproc_desc page_kp = {
 };
 SYSINIT_KT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp)
 
+#ifndef NO_SWAPPING
 /* the kernel process "vm_daemon"*/
 static void vm_daemon __P((void));
 static struct	proc *vmproc;
@@ -123,6 +124,7 @@ static struct kproc_desc vm_kp = {
 	&vmproc
 };
 SYSINIT_KT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp)
+#endif /* !NO_SWAPPING */
 
 
 int vm_pages_needed;		/* Event on which pageout daemon sleeps */
@@ -527,17 +529,6 @@ vm_pageout_map_deactivate_pages(map, entry, count, freeer)
 	return;
 }
 
-static void
-vm_req_vmdaemon()
-{
-	static int lastrun = 0;
-
-	if ((ticks > (lastrun + hz / 10)) || (ticks < lastrun)) {
-		wakeup(&vm_daemon_needed);
-		lastrun = ticks;
-	}
-}
-
 /*
  *	vm_pageout_scan does the dirty work for the pageout daemon.
  */
@@ -776,6 +767,7 @@ rescan1:
 				wakeup(&vfs_update_wakeup);
 			}
 		}
+#ifndef NO_SWAPPING
 		/*
 		 * now swap processes out if we are in low memory conditions
 		 */
@@ -784,12 +776,15 @@ rescan1:
 			vm_pageout_req_swapout = 1;
 			vm_req_vmdaemon();
 		}
+#endif
 	}
 
+#ifndef NO_SWAPPING
 	if ((cnt.v_inactive_count + cnt.v_free_count + cnt.v_cache_count) <
 	    (cnt.v_inactive_target + cnt.v_free_min)) {
 		vm_req_vmdaemon();
 	}
+#endif
 
 	/*
 	 * make sure that we have swap space -- if we are low on memory and
@@ -905,6 +900,18 @@ vm_pageout()
 	}
 }
 
+#ifndef NO_SWAPPING
+static void
+vm_req_vmdaemon()
+{
+	static int lastrun = 0;
+
+	if ((ticks > (lastrun + hz / 10)) || (ticks < lastrun)) {
+		wakeup(&vm_daemon_needed);
+		lastrun = ticks;
+	}
+}
+
 static void
 vm_daemon()
 {
@@ -981,3 +988,4 @@ restart:
 		}
 	}
 }
+#endif /* !NO_SWAPPING */