diff mbox

[3/3] aarch64: kvm: introduce CONFIG_KVM_MAX_VCPUS

Message ID 1379160656-28050-4-git-send-email-drjones@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andrew Jones Sept. 14, 2013, 12:10 p.m. UTC
Take CONFIG_KVM_MAX_VCPUS from arm32, but set the default to 8.

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 arch/arm64/include/asm/kvm_host.h |  7 ++++++-
 arch/arm64/kvm/Kconfig            | 11 +++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

Comments

Christoffer Dall Sept. 17, 2013, 9:34 p.m. UTC | #1
On Sat, Sep 14, 2013 at 02:10:56PM +0200, Andrew Jones wrote:
> Take CONFIG_KVM_MAX_VCPUS from arm32, but set the default to 8.
> 
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
>  arch/arm64/include/asm/kvm_host.h |  7 ++++++-
>  arch/arm64/kvm/Kconfig            | 11 +++++++++++
>  2 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 0859a4ddd1e7d..d1af8c49a5ca4 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -26,7 +26,12 @@
>  #include <asm/kvm_asm.h>
>  #include <asm/kvm_mmio.h>
>  
> -#define KVM_MAX_VCPUS 4
> +#if defined(CONFIG_KVM_MAX_VCPUS)
> +#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS
> +#else
> +#define KVM_MAX_VCPUS 0
> +#endif
> +
>  #define KVM_USER_MEM_SLOTS 32
>  #define KVM_PRIVATE_MEM_SLOTS 4
>  #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
> diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> index 21e90820bd23c..c9924b02e84f7 100644
> --- a/arch/arm64/kvm/Kconfig
> +++ b/arch/arm64/kvm/Kconfig
> @@ -35,6 +35,17 @@ config KVM_ARM_HOST
>  	---help---
>  	  Provides host support for ARM processors.
>  
> +config KVM_MAX_VCPUS
> +	int "Number maximum supported virtual CPUs per VM"
> +	depends on KVM_ARM_HOST
> +	default 8

That data structure gets really big with 8 max vcpus.  I think we should
keep this at 4 for now, a quad-core VM is quite reasonable for now.

> +	help
> +	  Static number of max supported virtual CPUs per VM.
> +
> +	  The default is set to the highest number of vcpus that
> +	  current hardware supports. Set to a lower number to save
> +	  some resources. Set to a higher number to test scalability.
> +
>  config KVM_ARM_VGIC
>  	bool
>  	depends on KVM_ARM_HOST && OF
> -- 
> 1.8.1.4
>
Gleb Natapov Sept. 18, 2013, 6:21 a.m. UTC | #2
On Tue, Sep 17, 2013 at 10:34:28PM +0100, Christoffer Dall wrote:
> On Sat, Sep 14, 2013 at 02:10:56PM +0200, Andrew Jones wrote:
> > Take CONFIG_KVM_MAX_VCPUS from arm32, but set the default to 8.
> > 
> > Signed-off-by: Andrew Jones <drjones@redhat.com>
> > ---
> >  arch/arm64/include/asm/kvm_host.h |  7 ++++++-
> >  arch/arm64/kvm/Kconfig            | 11 +++++++++++
> >  2 files changed, 17 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> > index 0859a4ddd1e7d..d1af8c49a5ca4 100644
> > --- a/arch/arm64/include/asm/kvm_host.h
> > +++ b/arch/arm64/include/asm/kvm_host.h
> > @@ -26,7 +26,12 @@
> >  #include <asm/kvm_asm.h>
> >  #include <asm/kvm_mmio.h>
> >  
> > -#define KVM_MAX_VCPUS 4
> > +#if defined(CONFIG_KVM_MAX_VCPUS)
> > +#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS
> > +#else
> > +#define KVM_MAX_VCPUS 0
> > +#endif
> > +
> >  #define KVM_USER_MEM_SLOTS 32
> >  #define KVM_PRIVATE_MEM_SLOTS 4
> >  #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
> > diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
> > index 21e90820bd23c..c9924b02e84f7 100644
> > --- a/arch/arm64/kvm/Kconfig
> > +++ b/arch/arm64/kvm/Kconfig
> > @@ -35,6 +35,17 @@ config KVM_ARM_HOST
> >  	---help---
> >  	  Provides host support for ARM processors.
> >  
> > +config KVM_MAX_VCPUS
> > +	int "Number maximum supported virtual CPUs per VM"
> > +	depends on KVM_ARM_HOST
> > +	default 8
> 
> That data structure gets really big with 8 max vcpus.  I think we should
> keep this at 4 for now, a quad-core VM is quite reasonable for now.
> 
Which data structure? vgic? IIRC with 8 vcpus it will be something like
500 bytes bigger then it is now.

--
			Gleb.
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diff mbox

Patch

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 0859a4ddd1e7d..d1af8c49a5ca4 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -26,7 +26,12 @@ 
 #include <asm/kvm_asm.h>
 #include <asm/kvm_mmio.h>
 
-#define KVM_MAX_VCPUS 4
+#if defined(CONFIG_KVM_MAX_VCPUS)
+#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS
+#else
+#define KVM_MAX_VCPUS 0
+#endif
+
 #define KVM_USER_MEM_SLOTS 32
 #define KVM_PRIVATE_MEM_SLOTS 4
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 21e90820bd23c..c9924b02e84f7 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -35,6 +35,17 @@  config KVM_ARM_HOST
 	---help---
 	  Provides host support for ARM processors.
 
+config KVM_MAX_VCPUS
+	int "Number maximum supported virtual CPUs per VM"
+	depends on KVM_ARM_HOST
+	default 8
+	help
+	  Static number of max supported virtual CPUs per VM.
+
+	  The default is set to the highest number of vcpus that
+	  current hardware supports. Set to a lower number to save
+	  some resources. Set to a higher number to test scalability.
+
 config KVM_ARM_VGIC
 	bool
 	depends on KVM_ARM_HOST && OF