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Re: [Xen-devel] [PATCH 1/2] cpu steal time accounting

To: Dan Hecht <dhecht@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 1/2] cpu steal time accounting
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Thu, 23 Feb 2006 08:48:00 +0000
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On 22 Feb 2006, at 23:58, Dan Hecht wrote:

The interface does not provide a way for a vcpu to atomically read the
entire set of time values { wallclock time, real time counter, available
time counter, stolen time counter }.  While it seems that such a
mechanism might be "nice" to have in theory, it seems unnecessary in
practice.  Indeed, real hardware rarely provides this functionality.

One nice side effect of having this feature is that the explicit stolen
time counter (or available time counter) can be dropped entirely from
the interface, since its value can be inferred from the real time
counter and available time counter (or stolen time counter).

I don't understand the last paragraph here. It's not true that, for example,
 available_time = real_time - stolen_time

 -- Keir

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