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RE: [Xen-devel] [RFC] Physical hot-add cpus and TSC

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>, "Xen-Devel (xen-devel@xxxxxxxxxxxxxxxxxxx)" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>
Subject: RE: [Xen-devel] [RFC] Physical hot-add cpus and TSC
From: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>
Date: Fri, 28 May 2010 09:36:59 -0700 (PDT)
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> Linux doesn't make strong
> guarantees to applications about TSC semantics, by synthesising TSC, or
> anything like that.

Working on that ;-)  IMHO, any non-privileged use of rdtsc,
even under the control of the kernel (e.g. vsyscall) has
potential issues in a virtual machine.  Except a VMware
VM, where the problem is completely solved.

But, as you know, many Linux kernel developers aren't too
interested in solving problems for Xen, so there's an
uphill battle :-(

> Anyhow, retreading this argument is not going to be fruitful
> It's fair to
> say that your definition is now also Xen's definition.

Sorry, I'm not trying to beat a dead horse.  I'm just
playing whack-a-mole and repeating arguments for a
new audience and a new corner case.  If you prefer, I
can take that offlist.

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