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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] Precise guest instruction count.
Date: Tue, 10 Mar 2009 01:55:22 +0000
References: <gp2o2g$k18$1@ger.gmane.org>
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To: qemu-devel@nongnu.org
Cc: Steffen Liebergeld <usenet@gmx.eu>

> So my question is how can I get accurate guest instruction count number?

-icount maintains an accurate count of the number of instructions executed. 
However for performance reasons the counter value is not valid at all times.

Also note that you can not assume that a whole TB is executed (because of MMU 
faults, or IO interrupts).

Even with -icount, qemu is only deterministic internally. Its behavior can 
still be influenced by external events. In usermode this could be any 
syscall. In system mode this could be mouse/keyboard input, modified disk 
images or network traffic (possibly other things I've missed).

If you need counts of specific instructions then you probably need to add 
explicit counters to the implementation of those instructions.

Paul