From owner-freebsd-hackers@FreeBSD.ORG  Tue Aug 19 01:22:29 2003
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To: Dan Nelson <dnelson@allantgroup.com>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Sun, 17 Aug 2003 16:16:27 CDT."
             <20030817211627.GC2653@dan.emsphone.com> 
Date: Tue, 19 Aug 2003 10:22:18 +0200
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cc: Robert Watson <rwatson@freebsd.org>
cc: Buckie <freebsd1@centrum.cz>
cc: freebsd-hackers@freebsd.org
Subject: Re: GEOM Gate. 
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In message <20030817211627.GC2653@dan.emsphone.com>, Dan Nelson writes:

>I think this just demonstrates that you should not run benchmarks with
>all your debugging flags enabled :)  Most people will not be running
>production systems with WITNESS, and parts of the kernel that bog down
>under the heavy load of WITNESS may work just fine on a regular kernal
>config.

To quote from src/UPDATING:

] 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.


-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.