From: Paul Brook <paul@codesourcery.com>
To: qemu-devel@nongnu.org
Cc: Steffen Liebergeld <usenet@gmx.eu>
Subject: Re: [Qemu-devel] Precise guest instruction count.
Date: Tue, 10 Mar 2009 01:55:22 +0000 [thread overview]
Message-ID: <200903100155.22875.paul@codesourcery.com> (raw)
In-Reply-To: <gp2o2g$k18$1@ger.gmane.org>
> 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
next prev parent reply other threads:[~2009-03-10 1:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-03-09 9:38 [Qemu-devel] Precise guest instruction count Steffen Liebergeld
2009-03-09 21:56 ` Laurent Desnogues
2009-03-11 10:33 ` [Qemu-devel] " Steffen Liebergeld
2009-03-11 10:42 ` Laurent Desnogues
2009-03-11 12:53 ` Steffen Liebergeld
2009-03-11 13:13 ` Paul Brook
2009-03-10 1:55 ` Paul Brook [this message]
2009-03-11 11:45 ` Steffen Liebergeld
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