PLASTER A WARNING THAT TELLS PEOPLE THAT CURRENT HAS DEBUGGING FEATURES

TURNED ON.

Submitted by: rwatson

Suggest -DNO_WERROR unless you are a developer when building a kernel.

Submitted by: mike

1 files changed, 22 insertions, 0 deletions

diff --git a/UPDATING b/UPDATING
index b84e1b4bd776..9f28da2765dd 100644
--- a/UPDATING
+++ b/UPDATING
@@ -5,6 +5,28 @@ This file is maintained and copyrighted by M. Warner Losh
 of file for further details.  For commonly done items, please see the
 COMMON ITEMS: section later in the file.
 
+NOTE TO PEOPLE WHO THINK THAT 5.0-CURRENT IS SLOW:
+	FreeBSD 5.0-CURRENT has many debugging features turned on, in
+	both the kernel and userland.  These features attempt to detect
+	incorrect use of system primitives, and encourage loud failure
+	through extra sanity checking and fail stop semantics.  They
+	also substantially impact system performance.  If you want to
+	do performance measurement, benchmarking, and optimization,
+	you'll want to turn them off.  This includes various WITNESS-
+	related kernel options, INVARIANTS, malloc debugging flags
+	in userland, and various verbose features in the kernel.  Many
+	developers choose to disable these features on build machines
+	to maximize performance.
+
+	In addition, IDE write caching is currently disabled by default
+	due to on-going concerns about disk write order and file system
+	integrity.  Re-enabling write caching can substantially improve
+	performance.
+
+20020225:
+	Warnings are now errors in the kernel.  Unless you are a developer,
+	you should add -DNO_WERROR to your make line.
+
 20020217:
 	sendmail 8.12.2 has been imported.  The sendmail binary is no
 	longer a set-user-ID root binary and the infrastructure to support