From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: [PATCH 2/3] kvm hypervisor : Add hypercalls to
	support pv-ticketlock
Date: Thu, 20 Jan 2011 09:49:35 -0800
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Cc: Xen-devel <xen-devel@lists.xensource.com>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
	Nick Piggin <npiggin@kernel.dk>, kvm@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Jan Beulich <JBeulich@novell.com>, Eric Dumazet <dada1@cosmosbay.com>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
	suzuki@in.ibm.com, Avi Kivity <avi@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	=?ISO-8859-1?Q?Am=E9rico_Wang?= <xiyou.wangcong@gmail.com>,
	Linux Virtualization <virtualization@lists.linux-foundation.org>
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On 01/20/2011 03:42 AM, Srivatsa Vaddagiri wrote:
> On Wed, Jan 19, 2011 at 10:53:52AM -0800, Jeremy Fitzhardinge wrote:
>>> The reason for wanting this should be clear I guess, it allows PI.
>> Well, if we can expand the spinlock to include an owner, then all this
>> becomes moot...
> How so? Having an owner will not eliminate the need for pv-ticketlocks
> afaict. We still need a mechanism to reduce latency in scheduling the next
> thread-in-waiting, which is achieved by your patches. 

No, sorry, I should have been clearer.  I meant that going to the effort
of not increasing the lock size to record "in slowpath" state.

    J