* [PATCH] x86 kconfig: Add recommendation to enable paravirt spinlock
@ 2013-10-21 16:05 Raghavendra K T
2013-10-21 16:30 ` Konrad Rzeszutek Wilk
0 siblings, 1 reply; 2+ messages in thread
From: Raghavendra K T @ 2013-10-21 16:05 UTC (permalink / raw)
To: mingo, hpa, x86, gleb, pbonzini, tglx
Cc: konrad.wilk, linux, linux-kernel, kvm, Raghavendra K T
Since paravirt spinlock optimization are in 3.12 kernel, we have
very good performance benefit for paravirtualized KVM / Xen kernel.
Also we no longer suffer from 5% side effect on native kernel.
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
---
Would like to thank Sander for spotting and suggesting this.
pvspinlock benefit on KVM link: https://lkml.org/lkml/2013/8/6/178
Attilio's tests on native kernel impact:
http://blog.xen.org/index.php/2012/05/11/benchmarking-the-new-pv-ticketlock-implementation/
arch/x86/Kconfig | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f67e839..4ba9d32 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -638,10 +638,10 @@ config PARAVIRT_SPINLOCKS
spinlock implementation with something virtualization-friendly
(for example, block the virtual CPU rather than spinning).
- Unfortunately the downside is an up to 5% performance hit on
- native kernels, with various workloads.
+ It has minimal impact on native kernels and gives nice performance
+ benefit for paravirtualized KVM / Xen kernels.
- If you are unsure how to answer this question, answer N.
+ If you are unsure how to answer this question, answer Y.
source "arch/x86/xen/Kconfig"
--
1.7.11.7
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] x86 kconfig: Add recommendation to enable paravirt spinlock
2013-10-21 16:05 [PATCH] x86 kconfig: Add recommendation to enable paravirt spinlock Raghavendra K T
@ 2013-10-21 16:30 ` Konrad Rzeszutek Wilk
0 siblings, 0 replies; 2+ messages in thread
From: Konrad Rzeszutek Wilk @ 2013-10-21 16:30 UTC (permalink / raw)
To: Raghavendra K T
Cc: mingo, hpa, x86, gleb, pbonzini, tglx, linux, linux-kernel, kvm
On Mon, Oct 21, 2013 at 09:35:08PM +0530, Raghavendra K T wrote:
> Since paravirt spinlock optimization are in 3.12 kernel, we have
> very good performance benefit for paravirtualized KVM / Xen kernel.
> Also we no longer suffer from 5% side effect on native kernel.
Yeey!
>
> Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
> ---
> Would like to thank Sander for spotting and suggesting this.
> pvspinlock benefit on KVM link: https://lkml.org/lkml/2013/8/6/178
>
> Attilio's tests on native kernel impact:
> http://blog.xen.org/index.php/2012/05/11/benchmarking-the-new-pv-ticketlock-implementation/
>
> arch/x86/Kconfig | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index f67e839..4ba9d32 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -638,10 +638,10 @@ config PARAVIRT_SPINLOCKS
> spinlock implementation with something virtualization-friendly
> (for example, block the virtual CPU rather than spinning).
>
> - Unfortunately the downside is an up to 5% performance hit on
> - native kernels, with various workloads.
> + It has minimal impact on native kernels and gives nice performance
> + benefit for paravirtualized KVM / Xen kernels.
>
> - If you are unsure how to answer this question, answer N.
> + If you are unsure how to answer this question, answer Y.
>
> source "arch/x86/xen/Kconfig"
>
> --
> 1.7.11.7
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2013-10-21 16:30 ` Konrad Rzeszutek Wilk
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