From 60363fb9f79a74440348d9ea5d505444e2028c90 Mon Sep 17 00:00:00 2001
From: Luigi Rizzo <luigi@FreeBSD.org>
Date: Sat, 1 Dec 2001 00:21:30 +0000
Subject: [PATCH] vm/vm_kern.c: rate limit (to once per second) diagnostic
 printf when 	you run out of mbuf address space.

kern/subr_mbuf.c: print a warning message when mb_alloc fails, again
	rate-limited to at most once per second. This covers other
	cases of mbuf allocation failures. Probably it also overlaps the
	one handled in vm/vm_kern.c, so maybe the latter should go away.

This warning will let us gradually remove the printf that are scattered
across most network drivers to report mbuf allocation failures.
Those are potentially dangerous, in that they are not rate-limited and
can easily cause systems to panic.

Unless there is disagreement (which does not seem to be the case
judging from the discussion on -net so far), and because this is
sort of a safety bugfix, I plan to commit a similar change to STABLE
during the weekend (it affects kern/uipc_mbuf.c there).

Discussed-with: jlemon, silby and -net
---
 sys/kern/subr_mbuf.c | 15 ++++++++++++++-
 sys/vm/vm_kern.c     | 10 ++++++++--
 2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/sys/kern/subr_mbuf.c b/sys/kern/subr_mbuf.c
index 596319d091c2..7c4ab83d0f66 100644
--- a/sys/kern/subr_mbuf.c
+++ b/sys/kern/subr_mbuf.c
@@ -621,9 +621,22 @@ mb_alloc(struct mb_lstmngr *mb_list, int how, short type)
 				   * steal from other lists.
 				   */
 					m = mb_alloc_wait(mb_list, type);
-				} else
+				} else {
+					/*
+					 * no way to indent this code decently
+					 * with 8-space tabs.
+					 */
+					static int last_report;
 					/* XXX: No consistency. */
 					mbstat.m_drops++;
+					if (ticks < last_report ||
+					   (ticks - last_report) >= hz) {
+						last_report = ticks;
+						printf(
+"mb_alloc for type %d failed, consider increase mbuf value.\n", type);
+					}
+
+				}
 			}
 		}
 	}
diff --git a/sys/vm/vm_kern.c b/sys/vm/vm_kern.c
index 7ab7c08d783c..2e5ea304a627 100644
--- a/sys/vm/vm_kern.c
+++ b/sys/vm/vm_kern.c
@@ -70,6 +70,7 @@
 
 #include <sys/param.h>
 #include <sys/systm.h>
+#include <sys/kernel.h>		/* for ticks and hz */
 #include <sys/lock.h>
 #include <sys/mutex.h>
 #include <sys/proc.h>
@@ -331,8 +332,13 @@ kmem_malloc(map, size, flags)
 	if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
 		vm_map_unlock(map);
 		if (map != kmem_map) {
-			printf("Out of mbuf address space!\n");
-			printf("Consider increasing NMBCLUSTERS\n");
+			static int last_report; /* when we did it (in ticks) */
+			if (ticks < last_report ||
+			    (ticks - last_report) >= hz) {
+				last_report = ticks;
+				printf("Out of mbuf address space!\n");
+				printf("Consider increasing NMBCLUSTERS\n");
+			}
 			goto bad;
 		}
 		if ((flags & M_NOWAIT) == 0)