From: marc.zyngier@arm.com (Marc Zyngier)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] ARM: KVM: Yield CPU when vcpu executes a WFE
Date: Tue, 08 Oct 2013 16:06:59 +0100 [thread overview]
Message-ID: <52541F93.4070503@arm.com> (raw)
In-Reply-To: <52541EA3.7010403@linux.vnet.ibm.com>
On 08/10/13 16:02, Raghavendra K T wrote:
> [...]
>>>> + kvm_vcpu_on_spin(vcpu);
>>>
>>> Could you also enable CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT for arm and
>>> check if ple handler logic helps further?
>>> we would ideally get one more optimization folded into ple handler if
>>> you enable that.
>>
>> Just gave it a go, and the results are slightly (but consistently)
>> worse. Over 10 runs:
>>
>> Without RELAX_INTERCEPT: Average run 3.3623s
>> With RELAX_INTERCEPT: Average run 3.4226s
>>
>> Not massive, but still noticeable. Any clue?
>
> Is it a 4x overcommit? Probably we would have hit the code
> overhead if it were small guests.
Only 2x overcommit (dual core host, quad vcpu guests).
> RELAX_INTERCEPT is worth enabling for large guests with
> overcommits.
I'll try something more aggressive as soon as I get the time. What do
you call a large guest? So far, the hard limit on ARM is 8 vcpus.
M.
--
Jazz is not dead. It just smells funny...
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <marc.zyngier@arm.com>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Raghavendra KT <raghavendra.kt.linux@gmail.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Christoffer Dall <christoffer.dall@linaro.org>
Subject: Re: [PATCH 1/2] ARM: KVM: Yield CPU when vcpu executes a WFE
Date: Tue, 08 Oct 2013 16:06:59 +0100 [thread overview]
Message-ID: <52541F93.4070503@arm.com> (raw)
In-Reply-To: <52541EA3.7010403@linux.vnet.ibm.com>
On 08/10/13 16:02, Raghavendra K T wrote:
> [...]
>>>> + kvm_vcpu_on_spin(vcpu);
>>>
>>> Could you also enable CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT for arm and
>>> check if ple handler logic helps further?
>>> we would ideally get one more optimization folded into ple handler if
>>> you enable that.
>>
>> Just gave it a go, and the results are slightly (but consistently)
>> worse. Over 10 runs:
>>
>> Without RELAX_INTERCEPT: Average run 3.3623s
>> With RELAX_INTERCEPT: Average run 3.4226s
>>
>> Not massive, but still noticeable. Any clue?
>
> Is it a 4x overcommit? Probably we would have hit the code
> overhead if it were small guests.
Only 2x overcommit (dual core host, quad vcpu guests).
> RELAX_INTERCEPT is worth enabling for large guests with
> overcommits.
I'll try something more aggressive as soon as I get the time. What do
you call a large guest? So far, the hard limit on ARM is 8 vcpus.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2013-10-08 15:06 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-07 15:40 [PATCH 0/2] ARM/arm64: KVM: Yield CPU when vcpu executes a WFE Marc Zyngier
2013-10-07 15:40 ` Marc Zyngier
2013-10-07 15:40 ` [PATCH 1/2] ARM: " Marc Zyngier
2013-10-07 15:40 ` Marc Zyngier
2013-10-07 16:04 ` Alexander Graf
2013-10-07 16:04 ` Alexander Graf
2013-10-07 16:16 ` Marc Zyngier
2013-10-07 16:16 ` Marc Zyngier
2013-10-07 16:30 ` Alexander Graf
2013-10-07 16:30 ` Alexander Graf
2013-10-07 16:53 ` Gleb Natapov
2013-10-07 16:53 ` Gleb Natapov
2013-10-09 13:09 ` Alexander Graf
2013-10-09 13:09 ` Alexander Graf
2013-10-09 13:26 ` Gleb Natapov
2013-10-09 13:26 ` Gleb Natapov
2013-10-09 14:18 ` Marc Zyngier
2013-10-09 14:18 ` Marc Zyngier
2013-10-09 14:50 ` Anup Patel
2013-10-09 14:50 ` Anup Patel
2013-10-09 14:52 ` Anup Patel
2013-10-09 14:52 ` Anup Patel
2013-10-09 14:59 ` Marc Zyngier
2013-10-09 14:59 ` Marc Zyngier
2013-10-09 15:10 ` Anup Patel
2013-10-09 15:10 ` Anup Patel
2013-10-09 15:17 ` Marc Zyngier
2013-10-09 15:17 ` Marc Zyngier
2013-10-09 15:17 ` Anup Patel
2013-10-09 15:17 ` Anup Patel
2013-10-07 16:55 ` Marc Zyngier
2013-10-07 16:55 ` Marc Zyngier
2013-10-08 11:26 ` Raghavendra KT
2013-10-08 11:26 ` Raghavendra KT
2013-10-08 12:43 ` Marc Zyngier
2013-10-08 12:43 ` Marc Zyngier
2013-10-08 15:02 ` Raghavendra K T
2013-10-08 15:02 ` Raghavendra K T
2013-10-08 15:06 ` Marc Zyngier [this message]
2013-10-08 15:06 ` Marc Zyngier
2013-10-08 15:13 ` Raghavendra K T
2013-10-08 15:13 ` Raghavendra K T
2013-10-08 16:09 ` Marc Zyngier
2013-10-08 16:09 ` Marc Zyngier
2013-10-07 15:40 ` [PATCH 2/2] arm64: " Marc Zyngier
2013-10-07 15:40 ` Marc Zyngier
2013-10-07 15:52 ` Bhushan Bharat-R65777
2013-10-07 15:52 ` Bhushan Bharat-R65777
2013-10-07 16:00 ` Marc Zyngier
2013-10-07 16:00 ` Marc Zyngier
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