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Date: Wed, 19 Jan 2011 23:59:41 +0530
From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Nick Piggin <npiggin@kernel.dk>,
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        "H. Peter Anvin" <hpa@zytor.com>,
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        Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
        kvm@vger.kernel.org, suzuki@in.ibm.com
Subject: Re: [PATCH 2/3] kvm hypervisor : Add hypercalls to support
 pv-ticketlock
Message-ID: <20110119182940.GA7235@linux.vnet.ibm.com>
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On Wed, Jan 19, 2011 at 06:21:12PM +0100, Peter Zijlstra wrote:
> I didn't really read the patch, and I totally forgot everything from
> when I looked at the Xen series, but does the Xen/KVM hypercall
> interface for this include the vcpu to await the kick from?

No not yet, for reasons you mention below.

> My guess is not, since the ticket locks used don't know who the owner
> is, which is of course, sad. There are FIFO spinlock implementations
> that can do this though.. although I think they all have a bigger memory
> footprint.
> 
> The reason for wanting this should be clear I guess, it allows PI.

Yeah - that would be good to experiment with.

- vatsa