* [PATCH] KVM: s390: change default halt poll to 50000
@ 2019-05-15 8:23 Christian Borntraeger
2019-05-15 10:22 ` David Hildenbrand
2019-05-15 11:34 ` Cornelia Huck
0 siblings, 2 replies; 5+ messages in thread
From: Christian Borntraeger @ 2019-05-15 8:23 UTC (permalink / raw)
To: Janosch Frank
Cc: KVM, Cornelia Huck, Christian Borntraeger, David Hildenbrand,
Paolo Bonzini, Radim Krčmář, Collin Walling,
Jason J . Herne
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)
--
2.19.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: s390: change default halt poll to 50000
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
1 sibling, 2 replies; 5+ messages in thread
From: David Hildenbrand @ 2019-05-15 10:22 UTC (permalink / raw)
To: Christian Borntraeger, Janosch Frank
Cc: KVM, Cornelia Huck, Paolo Bonzini, Radim Krčmář,
Collin Walling, Jason J . Herne
"KVM: s390: change default halt poll time to 50us
Recent measurements indicate that using 50us results in a reduced CPU
consumption, while still providing the benefit of halt polling. Let's
use 50us instead."
Acked-by: David Hildenbrand <david@redhat.com>
On 15.05.19 10:23, Christian Borntraeger 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)
>
--
Thanks,
David / dhildenb
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: s390: change default halt poll to 50000
2019-05-15 10:22 ` David Hildenbrand
@ 2019-05-15 10:26 ` Christian Borntraeger
2019-05-15 10:55 ` Janosch Frank
1 sibling, 0 replies; 5+ messages in thread
From: Christian Borntraeger @ 2019-05-15 10:26 UTC (permalink / raw)
To: David Hildenbrand, Janosch Frank
Cc: KVM, Cornelia Huck, Paolo Bonzini, Radim Krčmář,
Collin Walling, Jason J . Herne
On 15.05.19 12:22, David Hildenbrand wrote:
> "KVM: s390: change default halt poll time to 50us
>
> Recent measurements indicate that using 50us results in a reduced CPU
> consumption, while still providing the benefit of halt polling. Let's
> use 50us instead."
Yes, sounds better.
>
> Acked-by: David Hildenbrand <david@redhat.com>
>
>
>
> On 15.05.19 10:23, Christian Borntraeger 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)
>>
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: s390: change default halt poll to 50000
2019-05-15 10:22 ` David Hildenbrand
2019-05-15 10:26 ` Christian Borntraeger
@ 2019-05-15 10:55 ` Janosch Frank
1 sibling, 0 replies; 5+ messages in thread
From: Janosch Frank @ 2019-05-15 10:55 UTC (permalink / raw)
To: David Hildenbrand, Christian Borntraeger, Janosch Frank
Cc: KVM, Cornelia Huck, Paolo Bonzini, Radim Krčmář,
Collin Walling, Jason J . Herne
On 5/15/19 12:22 PM, David Hildenbrand wrote:
> "KVM: s390: change default halt poll time to 50us
>
> Recent measurements indicate that using 50us results in a reduced CPU
> consumption, while still providing the benefit of halt polling. Let's
> use 50us instead."
>
> Acked-by: David Hildenbrand <david@redhat.com>
With that change:
Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com>
>
>
>
> On 15.05.19 10:23, Christian Borntraeger 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)
>>
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: s390: change default halt poll to 50000
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 11:34 ` Cornelia Huck
1 sibling, 0 replies; 5+ messages in thread
From: Cornelia Huck @ 2019-05-15 11:34 UTC (permalink / raw)
To: Christian Borntraeger
Cc: Janosch Frank, KVM, David Hildenbrand, Paolo Bonzini,
Radim Krčmář, Collin Walling, Jason J . Herne
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>
^ permalink raw reply [flat|nested] 5+ messages in thread
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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
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