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From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Christoffer Dall <christoffer.dall@linaro.org>
Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Marc Zyngier <marc.zyngier@arm.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v2] arm/arm64: KVM: Properly account for guest CPU time
Date: Mon, 01 Jun 2015 11:21:19 +0200	[thread overview]
Message-ID: <556C240F.5070501@de.ibm.com> (raw)
In-Reply-To: <20150601090817.GA18722@cbox>

Am 01.06.2015 um 11:08 schrieb Christoffer Dall:

>>>
>>> Second, looking at the ppc and mips code, they seem to also call
>>> kvm_guest_exit() before enabling interrupts, so I don't understand how
>>> guest CPU time accounting works on those architectures.
>>
>> Not an expert here, but I assume mips has the same logic as arm so if your
>> patch is right for arm its probably also for mips.
>>
>> powerpc looks similar to what s390 does (not using the tick, instead it uses
>> a hw-timer) so this should be fine.
>>
> I wonder if we can simply enable HAVE_VIRT_CPU_ACCOUNTING_GEN and get
> this for free which would avoid the need for this patch?

Asssuming that HAVE_VIRT_CPU_ACCOUNTING_GEN behaves similar to 
HAVE_VIRT_CPU_ACCOUNTING on s390/power in respect to not rely on ticks
- yes it might work out. Can you give it a try?

Christian



WARNING: multiple messages have this Message-ID (diff)
From: borntraeger@de.ibm.com (Christian Borntraeger)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] arm/arm64: KVM: Properly account for guest CPU time
Date: Mon, 01 Jun 2015 11:21:19 +0200	[thread overview]
Message-ID: <556C240F.5070501@de.ibm.com> (raw)
In-Reply-To: <20150601090817.GA18722@cbox>

Am 01.06.2015 um 11:08 schrieb Christoffer Dall:

>>>
>>> Second, looking at the ppc and mips code, they seem to also call
>>> kvm_guest_exit() before enabling interrupts, so I don't understand how
>>> guest CPU time accounting works on those architectures.
>>
>> Not an expert here, but I assume mips has the same logic as arm so if your
>> patch is right for arm its probably also for mips.
>>
>> powerpc looks similar to what s390 does (not using the tick, instead it uses
>> a hw-timer) so this should be fine.
>>
> I wonder if we can simply enable HAVE_VIRT_CPU_ACCOUNTING_GEN and get
> this for free which would avoid the need for this patch?

Asssuming that HAVE_VIRT_CPU_ACCOUNTING_GEN behaves similar to 
HAVE_VIRT_CPU_ACCOUNTING on s390/power in respect to not rely on ticks
- yes it might work out. Can you give it a try?

Christian

  reply	other threads:[~2015-06-01  9:28 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-28 18:49 [PATCH v2] arm/arm64: KVM: Properly account for guest CPU time Christoffer Dall
2015-05-28 18:49 ` Christoffer Dall
2015-05-29 22:34 ` Mario Smarduch
2015-05-29 22:34   ` Mario Smarduch
2015-05-31  6:59   ` Christoffer Dall
2015-05-31  6:59     ` Christoffer Dall
2015-06-01 15:48     ` Mario Smarduch
2015-06-01 15:48       ` Mario Smarduch
2015-06-02  9:27       ` Christoffer Dall
2015-06-02  9:27         ` Christoffer Dall
2015-06-02 11:55         ` Christoffer Dall
2015-06-02 11:55           ` Christoffer Dall
2015-06-05 12:24         ` Mario Smarduch
2015-06-05 12:24           ` Mario Smarduch
2015-06-08 11:35           ` Christoffer Dall
2015-06-08 11:35             ` Christoffer Dall
2015-06-09 23:04             ` Mario Smarduch
2015-06-09 23:04               ` Mario Smarduch
2015-06-01  7:47 ` Christian Borntraeger
2015-06-01  7:47   ` Christian Borntraeger
2015-06-01  9:08   ` Christoffer Dall
2015-06-01  9:08     ` Christoffer Dall
2015-06-01  9:21     ` Christian Borntraeger [this message]
2015-06-01  9:21       ` Christian Borntraeger
2015-06-01 13:35       ` Christoffer Dall
2015-06-01 13:35         ` Christoffer Dall
2015-06-01 13:37         ` Christian Borntraeger
2015-06-01 13:37           ` Christian Borntraeger
2015-06-02  9:28           ` Christoffer Dall
2015-06-02  9:28             ` Christoffer Dall
2015-06-01 11:34   ` Paolo Bonzini
2015-06-01 11:34     ` Paolo Bonzini
2015-06-01 11:42     ` Christian Borntraeger
2015-06-01 11:42       ` Christian Borntraeger
2015-06-01 11:52       ` Paolo Bonzini
2015-06-01 11:52         ` Paolo Bonzini
2015-06-08 17:50 ` Marc Zyngier
2015-06-08 17:50   ` Marc Zyngier
2015-06-09 14:43   ` Christoffer Dall
2015-06-09 14:43     ` Christoffer Dall
2015-06-09 16:39     ` Marc Zyngier
2015-06-09 16:39       ` Marc Zyngier

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