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Re: [Xen-devel] [PATCH RFC v6 10/11] pvqspinlock, x86: Enable qspinlock PV support for KVM
- To: Waiman Long <waiman.long@xxxxxx>
- From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
- Date: Tue, 18 Mar 2014 09:18:13 +0100
- Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>, linux-kernel@vger., kvm@xxxxxxxxxxxxxxx, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx, Andi Kleen <andi@xxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Michel Lespinasse <walken@xxxxxxxxxx>, Alok Kataria <akataria@xxxxxxxxxx>, linux-arch@xxxxxxxxxxxxxxx, Gleb Natapov <gleb@xxxxxxxxxx>, x86@xxxxxxxxxx, Ingo Molnar <mingo@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>, Arnd Bergmann <arnd@xxxxxxxx>, Scott J Norton <scott.norton@xxxxxx>, Steven Rostedt <rostedt@xxxxxxxxxxx>, Chris Wright <chrisw@xxxxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Aswin Chandramouleeswaran <aswin@xxxxxx>, Chegu Vinod <chegu_vinod@xxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Oleg Nesterov <oleg@xxxxxxxxxx>
- Delivery-date: Tue, 18 Mar 2014 08:18:39 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
Il 17/03/2014 18:47, Waiman Long ha scritto:
Yeah, what I mean is that the patches that enable paravirtualization
should also take care of decreasing the unfair-lock jump label when
paravirtualization is enabled.
As there are people who don't like unfair lock at all, I prefer to give
them the option to turn this on or off instead of forcing them to always
use unfair lock in a PV guest.
I understand, but this is virtualization after all. A bad scheduler
decision means no progress at all. That's much worse than unfairness.
And also, KVM and Xen will stay fair, so if you want fairness just pick
a hypervisor that supports it.
Paolo
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