From: Cornelia Huck <cohuck@redhat.com>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "Janosch Frank" <frankja@linux.vnet.ibm.com>,
KVM <kvm@vger.kernel.org>, "David Hildenbrand" <david@redhat.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Collin Walling" <walling@linux.ibm.com>,
"Jason J . Herne" <jjherne@linux.ibm.com>
Subject: Re: [PATCH] KVM: s390: change default halt poll to 50000
Date: Wed, 15 May 2019 13:34:06 +0200 [thread overview]
Message-ID: <20190515133406.7b3ea902.cohuck@redhat.com> (raw)
In-Reply-To: <20190515082324.112755-1-borntraeger@de.ibm.com>
On Wed, 15 May 2019 10:23:24 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> older performance measurements indicated that 50000 vs 80000 reduces cpu
> consumption while still providing the benefit of halt polling. We had
> this change in the IBM KVM product, but it got lost so it never went
> upstream. Recent re-measurement indicate that 50k is still better than
> 80k.
>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
> arch/s390/include/asm/kvm_host.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index dbe254847e0d..cb63cc7bbf06 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -36,7 +36,7 @@
> */
> #define KVM_NR_IRQCHIPS 1
> #define KVM_IRQCHIP_NUM_PINS 4096
> -#define KVM_HALT_POLL_NS_DEFAULT 80000
> +#define KVM_HALT_POLL_NS_DEFAULT 50000
>
> /* s390-specific vcpu->requests bit members */
> #define KVM_REQ_ENABLE_IBS KVM_ARCH_REQ(0)
I trust your tests :)
Acked-by: Cornelia Huck <cohuck@redhat.com>
prev parent reply other threads:[~2019-05-15 11:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-15 8:23 [PATCH] KVM: s390: change default halt poll to 50000 Christian Borntraeger
2019-05-15 10:22 ` David Hildenbrand
2019-05-15 10:26 ` Christian Borntraeger
2019-05-15 10:55 ` Janosch Frank
2019-05-15 11:34 ` Cornelia Huck [this message]
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