From a91831a2616efe8f54f1581263071600ed0a1d0a Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Wed, 9 Jul 2014 19:11:57 +0000
Subject: [PATCH] Current code in sysctl proc.vmmap, which intent is to
 calculate the amount of resident pages, in fact calculates the amount of
 installed pte entries in the region.  Resident pages which were not
 soft-faulted yet are not counted.

Calculate the amount of resident pages by looking in the objects chain
backing the region.

Add a knob to disable the residency calculation at all.  For large
sparce regions, either previous or updated algorithm runs for too long
time, while several introspection tools do not need the (advisory) RSS
value at all.

PR:	kern/188911
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
---
 sys/kern/kern_proc.c | 85 ++++++++++++++++++++++++++------------------
 1 file changed, 51 insertions(+), 34 deletions(-)

diff --git a/sys/kern/kern_proc.c b/sys/kern/kern_proc.c
index e38d01169498..d917121ee61d 100644
--- a/sys/kern/kern_proc.c
+++ b/sys/kern/kern_proc.c
@@ -141,6 +141,10 @@ uma_zone_t proc_zone;
 int kstack_pages = KSTACK_PAGES;
 SYSCTL_INT(_kern, OID_AUTO, kstack_pages, CTLFLAG_RD, &kstack_pages, 0,
     "Kernel stack size in pages");
+static int vmmap_skip_res_cnt = 0;
+SYSCTL_INT(_kern, OID_AUTO, proc_vmmap_skip_resident_count, CTLFLAG_RW,
+    &vmmap_skip_res_cnt, 0,
+    "Skip calculation of the pages resident count in kern.proc.vmmap");
 
 CTASSERT(sizeof(struct kinfo_proc) == KINFO_PROC_SIZE);
 #ifdef COMPAT_FREEBSD32
@@ -2136,15 +2140,19 @@ int
 kern_proc_vmmap_out(struct proc *p, struct sbuf *sb)
 {
 	vm_map_entry_t entry, tmp_entry;
-	unsigned int last_timestamp;
+	struct vattr va;
+	vm_map_t map;
+	vm_page_t m;
+	vm_object_t obj, tobj, lobj;
 	char *fullpath, *freepath;
 	struct kinfo_vmentry *kve;
-	struct vattr va;
 	struct ucred *cred;
-	int error;
 	struct vnode *vp;
 	struct vmspace *vm;
-	vm_map_t map;
+	vm_pindex_t pindex;
+	vm_offset_t addr;
+	unsigned int last_timestamp;
+	int error;
 
 	PROC_LOCK_ASSERT(p, MA_OWNED);
 
@@ -2162,44 +2170,53 @@ kern_proc_vmmap_out(struct proc *p, struct sbuf *sb)
 	vm_map_lock_read(map);
 	for (entry = map->header.next; entry != &map->header;
 	    entry = entry->next) {
-		vm_object_t obj, tobj, lobj;
-		vm_offset_t addr;
-		vm_paddr_t locked_pa;
-		int mincoreinfo;
-
 		if (entry->eflags & MAP_ENTRY_IS_SUB_MAP)
 			continue;
 
 		bzero(kve, sizeof(*kve));
-
-		kve->kve_private_resident = 0;
 		obj = entry->object.vm_object;
 		if (obj != NULL) {
-			VM_OBJECT_RLOCK(obj);
+			for (tobj = obj; tobj != NULL;
+			    tobj = tobj->backing_object) {
+				VM_OBJECT_RLOCK(tobj);
+				lobj = tobj;
+			}
 			if (obj->shadow_count == 1)
 				kve->kve_private_resident =
 				    obj->resident_page_count;
-		}
-		kve->kve_resident = 0;
-		addr = entry->start;
-		while (addr < entry->end) {
-			locked_pa = 0;
-			mincoreinfo = pmap_mincore(map->pmap, addr, &locked_pa);
-			if (locked_pa != 0)
-				vm_page_unlock(PHYS_TO_VM_PAGE(locked_pa));
-			if (mincoreinfo & MINCORE_INCORE)
-				kve->kve_resident++;
-			if (mincoreinfo & MINCORE_SUPER)
-				kve->kve_flags |= KVME_FLAG_SUPER;
-			addr += PAGE_SIZE;
-		}
-
-		for (lobj = tobj = obj; tobj; tobj = tobj->backing_object) {
-			if (tobj != obj)
-				VM_OBJECT_RLOCK(tobj);
-			if (lobj != obj)
-				VM_OBJECT_RUNLOCK(lobj);
-			lobj = tobj;
+			if (vmmap_skip_res_cnt)
+				goto skip_resident_count;
+			for (addr = entry->start; addr < entry->end;
+			    addr += PAGE_SIZE) {
+				pindex = OFF_TO_IDX(entry->offset + addr -
+				    entry->start);
+				for (tobj = obj;;) {
+					m = vm_page_lookup(tobj, pindex);
+					if (m != NULL)
+						break;
+					if (tobj->backing_object == NULL)
+						break;
+					pindex += OFF_TO_IDX(
+					    tobj->backing_object_offset);
+					tobj = tobj->backing_object;
+				}
+				if (m != NULL) {
+					if (m->psind != 0 && addr +
+					    pagesizes[1] <= entry->end) {
+						kve->kve_flags |=
+						    KVME_FLAG_SUPER;
+					}
+					kve->kve_resident += 1;
+				}
+			}
+skip_resident_count:
+			for (tobj = obj; tobj != NULL;
+			    tobj = tobj->backing_object) {
+				if (tobj != obj && tobj != lobj)
+					VM_OBJECT_RUNLOCK(tobj);
+			}
+		} else {
+			lobj = NULL;
 		}
 
 		kve->kve_start = entry->start;
@@ -2229,7 +2246,7 @@ kern_proc_vmmap_out(struct proc *p, struct sbuf *sb)
 
 		freepath = NULL;
 		fullpath = "";
-		if (lobj) {
+		if (lobj != NULL) {
 			vp = NULL;
 			switch (lobj->type) {
 			case OBJT_DEFAULT: