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xen-devel
[Xen-devel] Re: [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls t
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To: |
Avi Kivity <avi@xxxxxxxxxx> |
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Subject: |
[Xen-devel] Re: [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls to support pv-ticketlock |
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From: |
Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx> |
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Date: |
Mon, 24 Oct 2011 17:57:34 +0530 |
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Cc: |
Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>, Dave Jiang <dave.jiang@xxxxxxxxx>, KVM <kvm@xxxxxxxxxxxxxxx>, Gleb Natapov <gleb@xxxxxxxxxx>, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>, Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>, x86@xxxxxxxxxx, Virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Marcelo Tosatti <mtosatti@xxxxxxxxxx>, Suzuki Poulose <suzuki@xxxxxxxxxxxxxxxxxx>, Xen <xen-devel@xxxxxxxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Sedat Dilek <sedat.dilek@xxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Yinghai Lu <yinghai@xxxxxxxxxx>, Greg Kroah-Hartman <gregkh@xxxxxxx>, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> |
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Tue, 25 Oct 2011 09:59:02 -0700 |
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References: |
<20111023190307.16364.35381.sendpatchset@xxxxxxxxxxxxxxxxxxxx> <20111023190558.16364.2136.sendpatchset@xxxxxxxxxxxxxxxxxxxx> <4EA53A7D.300@xxxxxxxxxx> |
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Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx> |
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Mutt/1.5.21 (2010-09-15) |
* Avi Kivity <avi@xxxxxxxxxx> [2011-10-24 12:14:21]:
> > +/*
> > + * kvm_pv_wait_for_kick_op : Block until kicked by either a KVM_HC_KICK_CPU
> > + * hypercall or a event like interrupt.
> > + *
> > + * @vcpu : vcpu which is blocking.
> > + */
> > +static void kvm_pv_wait_for_kick_op(struct kvm_vcpu *vcpu)
> > +{
[snip]
> > +}
>
> This hypercall can be replaced by a HLT instruction, no?
Good point. Assuming yield_on_hlt=1, that would allow the vcpu to be put
to sleep and let other vcpus make progress.
I guess with that change, we can also dropthe need for other hypercall
introduced in this patch (kvm_pv_kick_cpu_op()). Essentially a vcpu sleeping
because of HLT instruction can be woken up by a IPI issued by vcpu releasing a
lock.
- vatsa
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