From mboxrd@z Thu Jan  1 00:00:00 1970
From: Raghavendra K T <raghukt@linux.vnet.ibm.com>
Subject: Re: [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls to support
 pv-ticketlock
Date: Tue, 25 Oct 2011 23:54:02 +0530
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References: <20111023190307.16364.35381.sendpatchset@oc5400248562.ibm.com> <20111023190558.16364.2136.sendpatchset@oc5400248562.ibm.com> <4EA53A7D.300@redhat.com> <20111024122734.GA10634@linux.vnet.ibm.com> <4EA56385.9040302@redhat.com> <20111024135032.GB10634@linux.vnet.ibm.com>
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Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	"H. Peter Anvin" <hpa@zytor.com>, Gleb Natapov <gleb@redhat.com>,
	Virtualization <virtualization@lists.linux-foundation.org>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
	x86@kernel.org, KVM <kvm@vger.kernel.org>,
	Dave Jiang <dave.jiang@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	Xen <xen-devel@lists.xensource.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Yinghai Lu <yinghai@kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Ingo Molnar <mingo@redhat.com>, Rik van Riel <riel@redhat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Suzuki Poulose <suzuki@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>
To: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
	Avi Kivity <avi@redhat.com>
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On 10/24/2011 07:20 PM, Srivatsa Vaddagiri wrote:
> * Avi Kivity<avi@redhat.com>  [2011-10-24 15:09:25]:
>
>>> 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.
>>
>> Not if interrupts are disabled.
>
> Hmm yes ..so we need a kick hypercall then.
>

So then do also you foresee the need for directed yield at some point, 
to address LHP? provided we have good improvements to prove.