From: Avi Kivity <avi@redhat.com>
To: vatsa@linux.vnet.ibm.com
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
Gleb Natapov <gleb@redhat.com>,
linux-kernel@vger.kernel.org, npiggin@suse.de,
Jeremy Fitzhardinge <jeremy@goop.org>,
kvm@vger.kernel.org, bharata@in.ibm.com,
Balbir Singh <balbir@in.ibm.com>,
Jan Beulich <JBeulich@novell.com>
Subject: Re: [PATCH RFC 3/4] Paravirtualized spinlock implementation for KVM guests
Date: Mon, 02 Aug 2010 11:53:03 +0300 [thread overview]
Message-ID: <4C56876F.5000804@redhat.com> (raw)
In-Reply-To: <20100726061537.GC8402@linux.vnet.ibm.com>
On 07/26/2010 09:15 AM, Srivatsa Vaddagiri wrote:
> Paravirtual spinlock implementation for KVM guests, based heavily on Xen guest's
> spinlock implementation.
>
> +static void kvm_spin_unlock(struct arch_spinlock *lock)
> +{
> + struct kvm_spinlock *sl = (struct kvm_spinlock *)lock;
> +
> + ADD_STATS(released, 1);
> +
> + smp_wmb(); /* make sure no writes get moved after unlock */
> + sl->lock = 0; /* release lock */
> +}
Wait, no wakeup?
So it is a yield, not a sleep. I'm worried it could seriously impact
fairness when one non-contending guest (or non-pv) is overcommitted
together with a spin-yield guest.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2010-08-02 8:53 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-26 6:11 [PATCH RFC 0/4] Paravirt-spinlock implementation for KVM guests (Version 0) Srivatsa Vaddagiri
2010-07-26 6:13 ` [PATCH RFC 1/4] Debugfs support for reading an array of u32-type integers Srivatsa Vaddagiri
2010-07-26 6:14 ` [PATCH RFC 2/4] Add yield hypercall for KVM guests Srivatsa Vaddagiri
2010-07-26 17:19 ` Jeremy Fitzhardinge
2010-07-28 14:55 ` Srivatsa Vaddagiri
2010-08-02 8:40 ` Avi Kivity
2010-08-03 5:16 ` Srivatsa Vaddagiri
2010-08-03 5:33 ` Srivatsa Vaddagiri
2010-08-02 8:32 ` Avi Kivity
2010-08-02 14:42 ` Ryan Harper
2010-08-02 14:50 ` Avi Kivity
2010-08-02 15:08 ` Jeremy Fitzhardinge
2010-07-26 6:15 ` [PATCH RFC 3/4] Paravirtualized spinlock implementation " Srivatsa Vaddagiri
2010-08-02 8:48 ` Avi Kivity
2010-08-02 15:20 ` Jeremy Fitzhardinge
2010-08-03 6:59 ` Avi Kivity
2010-08-03 17:47 ` Jeremy Fitzhardinge
2010-08-02 8:53 ` Avi Kivity [this message]
2010-07-26 6:16 ` [PATCH RFC 4/4] Add yield hypercall support in Qemu Srivatsa Vaddagiri
2010-07-26 17:18 ` [PATCH RFC 0/4] Paravirt-spinlock implementation for KVM guests (Version 0) Jeremy Fitzhardinge
2010-07-28 14:47 ` Srivatsa Vaddagiri
2010-07-28 22:10 ` Konrad Rzeszutek Wilk
2010-07-28 22:42 ` Konrad Rzeszutek Wilk
2010-08-02 8:50 ` Avi Kivity
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