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xen-devel
[Xen-devel] Re: [PATCH 2/3] kvm hypervisor : Add hypercalls to support p
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To: |
Peter Zijlstra <peterz@xxxxxxxxxxxxx> |
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Subject: |
[Xen-devel] Re: [PATCH 2/3] kvm hypervisor : Add hypercalls to support pv-ticketlock |
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From: |
Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx> |
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Date: |
Thu, 20 Jan 2011 20:04:30 +0530 |
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Cc: |
Jeremy Fitzhardinge <jeremy@xxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>, Nick Piggin <npiggin@xxxxxxxxx>, kvm@xxxxxxxxxxxxxxx, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>, Eric Dumazet <dada1@xxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>, suzuki@xxxxxxxxxx, Avi Kivity <avi@xxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Américo Wang <xiyou.wangcong@xxxxxxxxx>, Linux Virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx> |
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Thu, 20 Jan 2011 06:35:35 -0800 |
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<cover.1289940821.git.jeremy.fitzhardinge@xxxxxxxxxx> <20110119164432.GA30669@xxxxxxxxxxxxxxxxxx> <20110119171239.GB726@xxxxxxxxxxxxxxxxxx> <1295457672.28776.144.camel@laptop> <4D373340.60608@xxxxxxxx> <20110120115958.GB11177@xxxxxxxxxxxxxxxxxx> <1295530906.28776.171.camel@laptop> |
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Mutt/1.5.20 (2009-06-14) |
On Thu, Jan 20, 2011 at 02:41:46PM +0100, Peter Zijlstra wrote:
> On Thu, 2011-01-20 at 17:29 +0530, Srivatsa Vaddagiri wrote:
> >
> > If we had a yield-to [1] sort of interface _and_ information on which vcpu
> > owns a lock, then lock-spinners can yield-to the owning vcpu,
>
> and then I'd nak it for being stupid ;-)
>
> really, yield*() is retarded, never even consider using it. If you've
> got the actual owner you can do full blown PI, which is tons better than
> a 'do-something-random' call.
Yes definitely that would be much better than yield-to.
> The only reason the whole non-virt pause loop filtering muck uses it is
> because it really doesn't know anything, and do-something is pretty much
> all it can do. Its a broken interface.
- vatsa
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