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Message-ID: <4826E1CB.6090500@BitWagon.com>
Date: Sun, 11 May 2008 05:08:43 -0700
From: John Reiser <jreiser@...Wagon.com>
To: Vegard Nossum <vegard.nossum@...il.com>
CC: Bart Van Assche <bart.vanassche@...il.com>,
Pekka Enberg <penberg@...helsinki.fi>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...e.hu>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Christoph Lameter <clameter@....com>,
Daniel Walker <dwalker@...sta.com>,
Andi Kleen <andi@...stfloor.org>,
Randy Dunlap <randy.dunlap@...cle.com>,
Josh Aune <luken@...er.org>, Pekka Paalanen <pq@....fi>
Subject: Re: [ANNOUNCE] kmemcheck v7
Vegard Nossum wrote:
> How is the speed of Valgrind+UML, does anybody know?
The speed of Valgrind+UML is the same as the speed of valgrind
on any application. On a 2GHz box it took about 2.5 minutes
to reach "login:" from a cold boot of UML (includes udev, etc.)
So if normal boot takes 15 seconds, then that's a factor of 10
slowdown: slow for interactivity, yet bearable for checking.
The memory-intensive portions (linear search, pointer chasing,
etc.) can be slower still, but loops that concentrate on
register arithmetic or conditional branching go faster.
There is almost no system wait time: normal device delays (disk,
network) get totally overlapped by CPU usage for grinding :-)
I'd like to have both kmemcheck and valgrind+UML, and use them
differently. Run kmemcheck all the time on a box or two as
"background trolling" for infrequent cases. Use valgrind+UML
for interactivity and programmable flexibility when hunting
specific bugs, or when hardware cannot be dedicated.
--
John Reiser, jreiser@...Wagon.com
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