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Re: [Xen-devel] [PATCH] turn off writable page tables

To: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] turn off writable page tables
From: Andrew Theurer <habanero@xxxxxxxxxx>
Date: Tue, 25 Jul 2006 21:25:14 -0500
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Ian Pratt wrote:
on Xeon MP processor, uniprocessor dom0 kernel, pae=y:

benchmark                c/s 10729 force_emulate
------------------------ --------- -------------
lmbench fork+exit:       469.5833  470.3913   usec, lower is better
lmbench fork+execve:     1241.0000 1225.7778  usec, lower is better
lmbench fork+/sbin/bash: 12190.000 12119.000  usec, lower is better

It's kinda weird that these scores are so close -- I guess its just
coincidence that we must be getting something like an average of 10-20
pte's updated per pagetable page and the cost of doing multiple emulates
perfectly balances the cost of unhooking/rehooking.
Ian, I'll try a small program which dirties a large chunk of memory. I'll also try the trace tool and see what we get.

Thanks,

Andrew


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