This is a rather large commit that encompasses the new swapper,

    changes to the VM system to support the new swapper, VM bug
    fixes, several VM optimizations, and some additional revamping of the
    VM code.  The specific bug fixes will be documented with additional
    forced commits.  This commit is somewhat rough in regards to code
    cleanup issues.

Reviewed by:	"John S. Dyson" <root@dyson.iquest.net>, "David Greenman" <dg@root.com>

1 files changed, 67 insertions, 42 deletions

diff --git a/sys/vm/vm_pager.c b/sys/vm/vm_pager.c
index 18df05d..62fe6e8 100644
--- a/sys/vm/vm_pager.c
+++ b/sys/vm/vm_pager.c
@@ -61,7 +61,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_pager.c,v 1.39 1998/10/31 15:31:29 peter Exp $
+ * $Id: vm_pager.c,v 1.40 1998/11/10 09:16:27 peter Exp $
  */
 
 /*
@@ -91,6 +91,8 @@ extern struct pagerops swappagerops;
 extern struct pagerops vnodepagerops;
 extern struct pagerops devicepagerops;
 
+int cluster_pbuf_freecnt = -1;	/* unlimited to begin with */
+
 static int dead_pager_getpages __P((vm_object_t, vm_page_t *, int, int));
 static vm_object_t dead_pager_alloc __P((void *, vm_ooffset_t, vm_prot_t,
 	vm_ooffset_t));
@@ -164,14 +166,15 @@ struct pagerops deadpagerops = {
 	NULL
 };
 
-static struct pagerops *pagertab[] = {
+struct pagerops *pagertab[] = {
 	&defaultpagerops,	/* OBJT_DEFAULT */
 	&swappagerops,		/* OBJT_SWAP */
 	&vnodepagerops,		/* OBJT_VNODE */
 	&devicepagerops,	/* OBJT_DEVICE */
 	&deadpagerops		/* OBJT_DEAD */
 };
-static int npagers = sizeof(pagertab) / sizeof(pagertab[0]);
+
+int npagers = sizeof(pagertab) / sizeof(pagertab[0]);
 
 /*
  * Kernel address space for mapping pages.
@@ -217,6 +220,8 @@ vm_pager_bufferinit()
 		bp->b_xflags = 0;
 	}
 
+	cluster_pbuf_freecnt = nswbuf / 2;
+
 	swapbkva = kmem_alloc_pageable(pager_map, nswbuf * MAXPHYS);
 	if (!swapbkva)
 		panic("Not enough pager_map VM space for physical buffers");
@@ -246,41 +251,21 @@ vm_pager_deallocate(object)
 	(*pagertab[object->type]->pgo_dealloc) (object);
 }
 
+/*
+ * vm_pager_get_pages() - inline, see vm/vm_pager.h
+ * vm_pager_put_pages() - inline, see vm/vm_pager.h
+ * vm_pager_has_page() - inline, see vm/vm_pager.h
+ * vm_pager_page_inserted() - inline, see vm/vm_pager.h
+ * vm_pager_page_removed() - inline, see vm/vm_pager.h
+ */
 
-int
-vm_pager_get_pages(object, m, count, reqpage)
-	vm_object_t object;
-	vm_page_t *m;
-	int count;
-	int reqpage;
-{
-	return ((*pagertab[object->type]->pgo_getpages)(object, m, count, reqpage));
-}
-
-int
-vm_pager_put_pages(object, m, count, flags, rtvals)
-	vm_object_t object;
-	vm_page_t *m;
-	int count;
-	int flags;
-	int *rtvals;
-{
-	return ((*pagertab[object->type]->pgo_putpages)(object, m, count, flags, rtvals));
-}
-
-boolean_t
-vm_pager_has_page(object, offset, before, after)
-	vm_object_t object;
-	vm_pindex_t offset;
-	int *before;
-	int *after;
-{
-	return ((*pagertab[object->type]->pgo_haspage) (object, offset, before, after));
-}
-
+#if 0
 /*
- * Called by pageout daemon before going back to sleep.
- * Gives pagers a chance to clean up any completed async pageing operations.
+ *	vm_pager_sync:
+ *
+ *	Called by pageout daemon before going back to sleep.
+ *	Gives pagers a chance to clean up any completed async pageing 
+ *	operations.
  */
 void
 vm_pager_sync()
@@ -292,6 +277,8 @@ vm_pager_sync()
 			(*(*pgops)->pgo_sync) ();
 }
 
+#endif
+
 vm_offset_t
 vm_pager_map_page(m)
 	vm_page_t m;
@@ -342,20 +329,42 @@ initpbuf(struct buf *bp) {
 
 /*
  * allocate a physical buffer
+ *
+ *	There are a limited number (nswbuf) of physical buffers.  We need
+ *	to make sure that no single subsystem is able to hog all of them,
+ *	so each subsystem implements a counter which is typically initialized
+ *	to 1/2 nswbuf.  getpbuf() decrements this counter in allocation and
+ *	increments it on release, and blocks if the counter hits zero.  A
+ *	subsystem may initialize the counter to -1 to disable the feature,
+ *	but it must still be sure to match up all uses of getpbuf() with 
+ *	relpbuf() using the same variable.
+ *
+ *	NOTE: pfreecnt can be NULL, but this 'feature' will be removed
+ *	relatively soon when the rest of the subsystems get smart about it. XXX
  */
 struct buf *
-getpbuf()
+getpbuf(pfreecnt)
+	int *pfreecnt;
 {
 	int s;
 	struct buf *bp;
 
 	s = splvm();
+
+	if (pfreecnt) {
+		while (*pfreecnt == 0) {
+			tsleep(pfreecnt, PVM, "wswbuf0", 0);
+		}
+	}
+
 	/* get a bp from the swap buffer header pool */
 	while ((bp = TAILQ_FIRST(&bswlist)) == NULL) {
 		bswneeded = 1;
-		tsleep(&bswneeded, PVM, "wswbuf", 0);
+		tsleep(&bswneeded, PVM, "wswbuf1", 0);
 	}
 	TAILQ_REMOVE(&bswlist, bp, b_freelist);
+	if (pfreecnt)
+		--*pfreecnt;
 	splx(s);
 
 	initpbuf(bp);
@@ -363,20 +372,27 @@ getpbuf()
 }
 
 /*
- * allocate a physical buffer, if one is available
+ * allocate a physical buffer, if one is available.
+ *
+ *	Note that there is no NULL hack here - all subsystems using this
+ *	call understand how to use pfreecnt.
  */
 struct buf *
-trypbuf()
+trypbuf(pfreecnt)
+	int *pfreecnt;
 {
 	int s;
 	struct buf *bp;
 
 	s = splvm();
-	if ((bp = TAILQ_FIRST(&bswlist)) == NULL) {
+	if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
 		splx(s);
 		return NULL;
 	}
 	TAILQ_REMOVE(&bswlist, bp, b_freelist);
+
+	--*pfreecnt;
+
 	splx(s);
 
 	initpbuf(bp);
@@ -386,10 +402,14 @@ trypbuf()
 
 /*
  * release a physical buffer
+ *
+ *	NOTE: pfreecnt can be NULL, but this 'feature' will be removed
+ *	relatively soon when the rest of the subsystems get smart about it. XXX
  */
 void
-relpbuf(bp)
+relpbuf(bp, pfreecnt)
 	struct buf *bp;
+	int *pfreecnt;
 {
 	int s;
 
@@ -403,6 +423,7 @@ relpbuf(bp)
 		crfree(bp->b_wcred);
 		bp->b_wcred = NOCRED;
 	}
+
 	if (bp->b_vp)
 		pbrelvp(bp);
 
@@ -415,5 +436,9 @@ relpbuf(bp)
 		bswneeded = 0;
 		wakeup(&bswneeded);
 	}
+	if (pfreecnt) {
+		if (++*pfreecnt == 1)
+			wakeup(pfreecnt);
+	}
 	splx(s);
 }