From: Andi Kleen <andi@firstfloor.org>
To: Avi Kivity <avi@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>, Gleb Natapov <gleb@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org, hpa@zytor.com,
mingo@elte.hu, npiggin@suse.de, tglx@linutronix.de,
mtosatti@redhat.com
Subject: Re: [PATCH] use unfair spinlock when running on hypervisor.
Date: Tue, 1 Jun 2010 19:27:30 +0200 [thread overview]
Message-ID: <20100601172730.GB11880@basil.fritz.box> (raw)
In-Reply-To: <4C053ACC.5020708@redhat.com>
On Tue, Jun 01, 2010 at 07:52:28PM +0300, Avi Kivity wrote:
> We are running everything on NUMA (since all modern machines are now NUMA).
> At what scale do the issues become observable?
On Intel platforms it's visible starting with 4 sockets.
>
>>> I understand that reason and do not propose to get back to old spinlock
>>> on physical HW! But with virtualization performance hit is unbearable.
>>>
>> Extreme unfairness can be unbearable too.
>>
>
> Well, the question is what happens first. In our experience, vcpu
> overcommit is a lot more painful. People will never see the NUMA
> unfairness issue if they can't use kvm due to the vcpu overcommit problem.
You really have to address both, if you don't fix them both
users will eventually into one of them and be unhappy.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2010-06-01 17:27 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-01 9:35 [PATCH] use unfair spinlock when running on hypervisor Gleb Natapov
2010-06-01 15:53 ` Andi Kleen
2010-06-01 16:24 ` Gleb Natapov
2010-06-01 16:38 ` Andi Kleen
2010-06-01 16:52 ` Avi Kivity
2010-06-01 17:27 ` Andi Kleen [this message]
2010-06-02 2:51 ` Avi Kivity
2010-06-02 5:26 ` Srivatsa Vaddagiri
2010-06-02 8:50 ` Andi Kleen
2010-06-02 9:00 ` Avi Kivity
2010-06-03 4:20 ` Srivatsa Vaddagiri
2010-06-03 4:51 ` Eric Dumazet
2010-06-03 5:38 ` Srivatsa Vaddagiri
2010-06-03 8:52 ` Andi Kleen
2010-06-03 9:26 ` Srivatsa Vaddagiri
2010-06-03 10:22 ` Nick Piggin
2010-06-03 10:38 ` Nick Piggin
2010-06-03 12:04 ` Srivatsa Vaddagiri
2010-06-03 12:38 ` Nick Piggin
2010-06-03 12:58 ` Srivatsa Vaddagiri
2010-06-03 13:04 ` Srivatsa Vaddagiri
2010-06-03 13:45 ` Nick Piggin
2010-06-03 14:48 ` Srivatsa Vaddagiri
2010-06-03 15:17 ` Andi Kleen
2010-06-03 15:35 ` Nick Piggin
2010-06-03 17:25 ` Andi Kleen
2010-06-01 17:39 ` Valdis.Kletnieks
2010-06-02 2:46 ` Avi Kivity
2010-06-02 7:39 ` H. Peter Anvin
2010-06-01 17:54 ` john cooper
2010-06-01 19:36 ` Andi Kleen
2010-06-03 11:06 ` David Woodhouse
2010-06-03 15:15 ` Andi Kleen
2010-06-01 21:39 ` Eric Dumazet
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