From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Northup <digitaleric@google.com>
Subject: Re: [PATCH 06/13] x86/ticketlock: add slowpath logic
Date: Fri, 2 Sep 2011 11:46:08 -0700
Message-ID: <CAG7+5M0s76O_TWBaoY2KU+WeEoJYEhkLLDXfg81WHYNvavH3yw@mail.gmail.com>
References: <cover.1314922370.git.jeremy.fitzhardinge@citrix.com>
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To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Linus Torvalds <torvalds@linux-foundation.org>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>, the arch/x86 maintainers <x86@kernel.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Nick Piggin <npiggin@kernel.dk>, Avi Kivity <avi@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>, KVM <kvm@vger.kernel.org>, Andi Kleen <andi@firstfloor.org>, Xen Devel <xen-devel@lists.xensource.com>, Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
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On Thu, Sep 1, 2011 at 5:54 PM, Jeremy Fitzhardinge <jeremy@goop.org> w=
rote:
> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
>
> Maintain a flag in both LSBs of the ticket lock which indicates wheth=
er
> anyone is in the lock slowpath and may need kicking when the current
> holder unlocks. =A0The flags are set when the first locker enters
> the slowpath, and cleared when unlocking to an empty queue.

Are there actually two flags maintained?  I only see the one in the
ticket tail getting set/cleared/tested.