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From: Waiman Long <waiman.long@hp.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
	Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
	kvm@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
	virtualization@lists.linux-foundation.org,
	Andi Kleen <andi@firstfloor.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Michel Lespinasse <walken@google.com>,
	Alok Kataria <akataria@vmware.com>,
	linux-arch@vger.kernel.org, Gleb Natapov <gleb@redhat.com>,
	x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
	xen-devel@lists.xenproject.org,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Scott J Norton <scott.norton@hp.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Chris Wright <chrisw@sous-sol.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Aswin Chandramouleeswaran <aswin@hp.com>,
	Chegu Vinod <chegu_vinod@hp.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Oleg Nesterov <oleg@redhat.com>, linux-kernel@vger.
Subject: Re: [PATCH v7 10/11] pvqspinlock, x86: Enable qspinlock PV support for KVM
Date: Fri, 21 Mar 2014 17:41:34 -0400	[thread overview]
Message-ID: <532CB20E.6060603@hp.com> (raw)
In-Reply-To: <532B668A.4010208@redhat.com>

On 03/20/2014 06:07 PM, Paolo Bonzini wrote:
> Il 19/03/2014 21:14, Waiman Long ha scritto:
>> This patch adds the necessary KVM specific code to allow KVM to support
>> the sleeping and CPU kicking operations needed by the queue spinlock PV
>> code.
>
> The remaining problem of this patch is that you cannot get the 
> generically optimal configuration: qspinlock on baremetal, PV 
> qspinlock on KVM/Xen, unfair qspinlock on VMware/Hyper-V.  You really 
> need to disable unfair locks in kvm_spinlock_init.
>
> Paolo
>

So you are suggesting that it is not a good idea to have both unfair 
lock & PV be enabled together. Right?

In order to disable unfair locks in kvm_spinlock_init(), it has to run 
after the unfair lock init code. Do you guys know what determine the 
init function execution sequence?

-Longman

  parent reply	other threads:[~2014-03-21 21:41 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-19 20:13 [PATCH v7 00/11] qspinlock: a 4-byte queue spinlock with PV support Waiman Long
2014-03-19 20:13 ` [PATCH v7 01/11] qspinlock: A generic 4-byte queue spinlock implementation Waiman Long
2014-03-19 20:14 ` [PATCH v7 02/11] qspinlock, x86: Enable x86-64 to use queue spinlock Waiman Long
2014-03-19 20:24   ` Konrad Rzeszutek Wilk
2014-03-21  3:36     ` Waiman Long
2014-03-19 20:14 ` [PATCH v7 03/11] qspinlock: More optimized code for smaller NR_CPUS Waiman Long
2014-03-19 20:14 ` [PATCH v7 04/11] qspinlock: Optimized code path for 2 contending tasks Waiman Long
2014-03-19 20:14 ` [PATCH v7 05/11] pvqspinlock, x86: Allow unfair spinlock in a PV guest Waiman Long
2014-03-19 20:14 ` [PATCH v7 06/11] pvqspinlock, x86: Allow unfair queue spinlock in a KVM guest Waiman Long
2014-03-20 22:01   ` Paolo Bonzini
2014-03-20 22:01     ` Paolo Bonzini
2014-03-20 22:29     ` H. Peter Anvin
2014-03-20 22:29       ` H. Peter Anvin
2014-03-20 22:40       ` Paolo Bonzini
2014-03-20 22:40         ` Paolo Bonzini
2014-03-21 21:27     ` Waiman Long
2014-03-19 20:14 ` [PATCH v7 07/11] pvqspinlock, x86: Allow unfair queue spinlock in a XEN guest Waiman Long
2014-03-19 20:28   ` Konrad Rzeszutek Wilk
2014-03-21  3:40     ` Waiman Long
2014-03-19 20:14 ` [PATCH v7 08/11] pvqspinlock, x86: Rename paravirt_ticketlocks_enabled Waiman Long
2014-03-19 20:14 ` [PATCH v7 09/11] pvqspinlock, x86: Add qspinlock para-virtualization support Waiman Long
2014-03-19 20:14 ` [PATCH v7 10/11] pvqspinlock, x86: Enable qspinlock PV support for KVM Waiman Long
2014-03-20 22:07   ` Paolo Bonzini
2014-03-20 22:07     ` Paolo Bonzini
2014-03-21 21:41     ` Waiman Long [this message]
2014-03-19 20:14 ` [PATCH RFC v7 11/11] pvqspinlock, x86: Enable qspinlock PV support for XEN Waiman Long

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