| Message ID | 1379160656-28050-3-git-send-email-drjones@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, Sep 14, 2013 at 02:10:55PM +0200, Andrew Jones wrote: > Drop the _ARM_ part of the name. We can then introduce a config option > like this to aarch64 and other arches using the same name - allowing > grep to show them all. Also update the help text to describe the option > more completely. > > Signed-off-by: Andrew Jones <drjones@redhat.com> > --- > arch/arm/include/asm/kvm_host.h | 4 ++-- > arch/arm/kvm/Kconfig | 8 ++++---- > 2 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > index 7d22517d80711..c614d3eb176c6 100644 > --- a/arch/arm/include/asm/kvm_host.h > +++ b/arch/arm/include/asm/kvm_host.h > @@ -25,8 +25,8 @@ > #include <asm/fpstate.h> > #include <kvm/arm_arch_timer.h> > > -#if defined(CONFIG_KVM_ARM_MAX_VCPUS) > -#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS > +#if defined(CONFIG_KVM_MAX_VCPUS) > +#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS > #else > #define KVM_MAX_VCPUS 0 > #endif > diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig > index ebf5015508b52..de63bfccb3eb5 100644 > --- a/arch/arm/kvm/Kconfig > +++ b/arch/arm/kvm/Kconfig > @@ -40,16 +40,16 @@ config KVM_ARM_HOST > ---help--- > Provides host support for ARM processors. > > -config KVM_ARM_MAX_VCPUS > +config KVM_MAX_VCPUS > int "Number maximum supported virtual CPUs per VM" > depends on KVM_ARM_HOST > default 4 > help > Static number of max supported virtual CPUs per VM. > > - If you choose a high number, the vcpu structures will be quite > - large, so only choose a reasonable number that you expect to > - actually use. I do no see why on ARM vcpu structure size depends on KVM_ARM_MAX_VCPUS. Can somebody point me to it. > + 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 "KVM support for Virtual GIC" > -- > 1.8.1.4 -- Gleb.
On 15/09/13 10:30, Gleb Natapov wrote: > On Sat, Sep 14, 2013 at 02:10:55PM +0200, Andrew Jones wrote: >> Drop the _ARM_ part of the name. We can then introduce a config option >> like this to aarch64 and other arches using the same name - allowing >> grep to show them all. Also update the help text to describe the option >> more completely. >> >> Signed-off-by: Andrew Jones <drjones@redhat.com> >> --- >> arch/arm/include/asm/kvm_host.h | 4 ++-- >> arch/arm/kvm/Kconfig | 8 ++++---- >> 2 files changed, 6 insertions(+), 6 deletions(-) >> >> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h >> index 7d22517d80711..c614d3eb176c6 100644 >> --- a/arch/arm/include/asm/kvm_host.h >> +++ b/arch/arm/include/asm/kvm_host.h >> @@ -25,8 +25,8 @@ >> #include <asm/fpstate.h> >> #include <kvm/arm_arch_timer.h> >> >> -#if defined(CONFIG_KVM_ARM_MAX_VCPUS) >> -#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS >> +#if defined(CONFIG_KVM_MAX_VCPUS) >> +#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS >> #else >> #define KVM_MAX_VCPUS 0 >> #endif >> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig >> index ebf5015508b52..de63bfccb3eb5 100644 >> --- a/arch/arm/kvm/Kconfig >> +++ b/arch/arm/kvm/Kconfig >> @@ -40,16 +40,16 @@ config KVM_ARM_HOST >> ---help--- >> Provides host support for ARM processors. >> >> -config KVM_ARM_MAX_VCPUS >> +config KVM_MAX_VCPUS >> int "Number maximum supported virtual CPUs per VM" >> depends on KVM_ARM_HOST >> default 4 >> help >> Static number of max supported virtual CPUs per VM. >> >> - If you choose a high number, the vcpu structures will be quite >> - large, so only choose a reasonable number that you expect to >> - actually use. > I do no see why on ARM vcpu structure size depends on KVM_ARM_MAX_VCPUS. > Can somebody point me to it. There's a number of indirections, but here you go: arch/arm/include/asm/kvm_host.h:#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS include/kvm/arm_vgic.h:#define VGIC_MAX_CPUS KVM_MAX_VCPUS include/kvm/arm_vgic.h:#if (VGIC_MAX_CPUS > 8) include/kvm/arm_vgic.h: } percpu[VGIC_MAX_CPUS]; include/kvm/arm_vgic.h: u32 percpu[VGIC_MAX_CPUS][VGIC_NR_PRIVATE_IRQS / 4]; include/kvm/arm_vgic.h: u8 irq_sgi_sources[VGIC_MAX_CPUS][VGIC_NR_SGIS]; include/kvm/arm_vgic.h: struct vgic_bitmap irq_spi_target[VGIC_MAX_CPUS]; Basically, the GIC emulation data structures are sized on the number of VCPUs (as well as the number of supported interrupts). M.
On Mon, Sep 16, 2013 at 09:09:27AM +0100, Marc Zyngier wrote: > On 15/09/13 10:30, Gleb Natapov wrote: > > On Sat, Sep 14, 2013 at 02:10:55PM +0200, Andrew Jones wrote: > >> Drop the _ARM_ part of the name. We can then introduce a config option > >> like this to aarch64 and other arches using the same name - allowing > >> grep to show them all. Also update the help text to describe the option > >> more completely. > >> > >> Signed-off-by: Andrew Jones <drjones@redhat.com> > >> --- > >> arch/arm/include/asm/kvm_host.h | 4 ++-- > >> arch/arm/kvm/Kconfig | 8 ++++---- > >> 2 files changed, 6 insertions(+), 6 deletions(-) > >> > >> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > >> index 7d22517d80711..c614d3eb176c6 100644 > >> --- a/arch/arm/include/asm/kvm_host.h > >> +++ b/arch/arm/include/asm/kvm_host.h > >> @@ -25,8 +25,8 @@ > >> #include <asm/fpstate.h> > >> #include <kvm/arm_arch_timer.h> > >> > >> -#if defined(CONFIG_KVM_ARM_MAX_VCPUS) > >> -#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS > >> +#if defined(CONFIG_KVM_MAX_VCPUS) > >> +#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS > >> #else > >> #define KVM_MAX_VCPUS 0 > >> #endif > >> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig > >> index ebf5015508b52..de63bfccb3eb5 100644 > >> --- a/arch/arm/kvm/Kconfig > >> +++ b/arch/arm/kvm/Kconfig > >> @@ -40,16 +40,16 @@ config KVM_ARM_HOST > >> ---help--- > >> Provides host support for ARM processors. > >> > >> -config KVM_ARM_MAX_VCPUS > >> +config KVM_MAX_VCPUS > >> int "Number maximum supported virtual CPUs per VM" > >> depends on KVM_ARM_HOST > >> default 4 > >> help > >> Static number of max supported virtual CPUs per VM. > >> > >> - If you choose a high number, the vcpu structures will be quite > >> - large, so only choose a reasonable number that you expect to > >> - actually use. > > I do no see why on ARM vcpu structure size depends on KVM_ARM_MAX_VCPUS. > > Can somebody point me to it. > > There's a number of indirections, but here you go: > arch/arm/include/asm/kvm_host.h:#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS > > include/kvm/arm_vgic.h:#define VGIC_MAX_CPUS KVM_MAX_VCPUS > > include/kvm/arm_vgic.h:#if (VGIC_MAX_CPUS > 8) > include/kvm/arm_vgic.h: } percpu[VGIC_MAX_CPUS]; > include/kvm/arm_vgic.h: u32 percpu[VGIC_MAX_CPUS][VGIC_NR_PRIVATE_IRQS / 4]; > include/kvm/arm_vgic.h: u8 irq_sgi_sources[VGIC_MAX_CPUS][VGIC_NR_SGIS]; > include/kvm/arm_vgic.h: struct vgic_bitmap irq_spi_target[VGIC_MAX_CPUS]; > > Basically, the GIC emulation data structures are sized on the number of VCPUs > (as well as the number of supported interrupts). > But vgic is per VM though, not per cpu as far as I can see, so the overhead is also per VM, no? Is VGIC_MAX_CPUS limit architectural or juts an implementation detail? -- Gleb.
On 16/09/13 09:32, Gleb Natapov wrote: > On Mon, Sep 16, 2013 at 09:09:27AM +0100, Marc Zyngier wrote: >> On 15/09/13 10:30, Gleb Natapov wrote: >>> On Sat, Sep 14, 2013 at 02:10:55PM +0200, Andrew Jones wrote: >>>> Drop the _ARM_ part of the name. We can then introduce a config option >>>> like this to aarch64 and other arches using the same name - allowing >>>> grep to show them all. Also update the help text to describe the option >>>> more completely. >>>> >>>> Signed-off-by: Andrew Jones <drjones@redhat.com> >>>> --- >>>> arch/arm/include/asm/kvm_host.h | 4 ++-- >>>> arch/arm/kvm/Kconfig | 8 ++++---- >>>> 2 files changed, 6 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h >>>> index 7d22517d80711..c614d3eb176c6 100644 >>>> --- a/arch/arm/include/asm/kvm_host.h >>>> +++ b/arch/arm/include/asm/kvm_host.h >>>> @@ -25,8 +25,8 @@ >>>> #include <asm/fpstate.h> >>>> #include <kvm/arm_arch_timer.h> >>>> >>>> -#if defined(CONFIG_KVM_ARM_MAX_VCPUS) >>>> -#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS >>>> +#if defined(CONFIG_KVM_MAX_VCPUS) >>>> +#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS >>>> #else >>>> #define KVM_MAX_VCPUS 0 >>>> #endif >>>> diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig >>>> index ebf5015508b52..de63bfccb3eb5 100644 >>>> --- a/arch/arm/kvm/Kconfig >>>> +++ b/arch/arm/kvm/Kconfig >>>> @@ -40,16 +40,16 @@ config KVM_ARM_HOST >>>> ---help--- >>>> Provides host support for ARM processors. >>>> >>>> -config KVM_ARM_MAX_VCPUS >>>> +config KVM_MAX_VCPUS >>>> int "Number maximum supported virtual CPUs per VM" >>>> depends on KVM_ARM_HOST >>>> default 4 >>>> help >>>> Static number of max supported virtual CPUs per VM. >>>> >>>> - If you choose a high number, the vcpu structures will be quite >>>> - large, so only choose a reasonable number that you expect to >>>> - actually use. >>> I do no see why on ARM vcpu structure size depends on KVM_ARM_MAX_VCPUS. >>> Can somebody point me to it. >> >> There's a number of indirections, but here you go: >> arch/arm/include/asm/kvm_host.h:#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS >> >> include/kvm/arm_vgic.h:#define VGIC_MAX_CPUS KVM_MAX_VCPUS >> >> include/kvm/arm_vgic.h:#if (VGIC_MAX_CPUS > 8) >> include/kvm/arm_vgic.h: } percpu[VGIC_MAX_CPUS]; >> include/kvm/arm_vgic.h: u32 percpu[VGIC_MAX_CPUS][VGIC_NR_PRIVATE_IRQS / 4]; >> include/kvm/arm_vgic.h: u8 irq_sgi_sources[VGIC_MAX_CPUS][VGIC_NR_SGIS]; >> include/kvm/arm_vgic.h: struct vgic_bitmap irq_spi_target[VGIC_MAX_CPUS]; >> >> Basically, the GIC emulation data structures are sized on the number of VCPUs >> (as well as the number of supported interrupts). >> > But vgic is per VM though, not per cpu as far as I can see, so the > overhead is also per VM, no? Is VGIC_MAX_CPUS limit architectural or > juts an implementation detail? Indeed, the MAX_VCPU overhead is per VM. The MAX_IRQS overhead is both per-vm and per-vcpu. The GICv2 architecture has a limit of 8 CPUs - not at all an implementation detail. GICv3 remove this limitation. M.
On Sat, Sep 14, 2013 at 02:10:55PM +0200, Andrew Jones wrote: > Drop the _ARM_ part of the name. We can then introduce a config option > like this to aarch64 and other arches using the same name - allowing > grep to show them all. Also update the help text to describe the option > more completely. > > Signed-off-by: Andrew Jones <drjones@redhat.com> > --- > arch/arm/include/asm/kvm_host.h | 4 ++-- > arch/arm/kvm/Kconfig | 8 ++++---- > 2 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > index 7d22517d80711..c614d3eb176c6 100644 > --- a/arch/arm/include/asm/kvm_host.h > +++ b/arch/arm/include/asm/kvm_host.h > @@ -25,8 +25,8 @@ > #include <asm/fpstate.h> > #include <kvm/arm_arch_timer.h> > > -#if defined(CONFIG_KVM_ARM_MAX_VCPUS) > -#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS > +#if defined(CONFIG_KVM_MAX_VCPUS) > +#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS > #else > #define KVM_MAX_VCPUS 0 > #endif > diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig > index ebf5015508b52..de63bfccb3eb5 100644 > --- a/arch/arm/kvm/Kconfig > +++ b/arch/arm/kvm/Kconfig > @@ -40,16 +40,16 @@ config KVM_ARM_HOST > ---help--- > Provides host support for ARM processors. > > -config KVM_ARM_MAX_VCPUS > +config KVM_MAX_VCPUS > int "Number maximum supported virtual CPUs per VM" > depends on KVM_ARM_HOST > default 4 > help > Static number of max supported virtual CPUs per VM. > > - If you choose a high number, the vcpu structures will be quite > - large, so only choose a reasonable number that you expect to > - actually use. > + 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. Consider rephrasing the "Set to a lower number..." sentence to something like "Choosing a lower number decreases the size of the VM data structure.". Also, please rephrase or get rid of the "Set to a higher number to test scalability." sentence; you increase this value to be able to be able to run more VCPUs (for whatever reason).
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h index 7d22517d80711..c614d3eb176c6 100644 --- a/arch/arm/include/asm/kvm_host.h +++ b/arch/arm/include/asm/kvm_host.h @@ -25,8 +25,8 @@ #include <asm/fpstate.h> #include <kvm/arm_arch_timer.h> -#if defined(CONFIG_KVM_ARM_MAX_VCPUS) -#define KVM_MAX_VCPUS CONFIG_KVM_ARM_MAX_VCPUS +#if defined(CONFIG_KVM_MAX_VCPUS) +#define KVM_MAX_VCPUS CONFIG_KVM_MAX_VCPUS #else #define KVM_MAX_VCPUS 0 #endif diff --git a/arch/arm/kvm/Kconfig b/arch/arm/kvm/Kconfig index ebf5015508b52..de63bfccb3eb5 100644 --- a/arch/arm/kvm/Kconfig +++ b/arch/arm/kvm/Kconfig @@ -40,16 +40,16 @@ config KVM_ARM_HOST ---help--- Provides host support for ARM processors. -config KVM_ARM_MAX_VCPUS +config KVM_MAX_VCPUS int "Number maximum supported virtual CPUs per VM" depends on KVM_ARM_HOST default 4 help Static number of max supported virtual CPUs per VM. - If you choose a high number, the vcpu structures will be quite - large, so only choose a reasonable number that you expect to - actually use. + 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 "KVM support for Virtual GIC"
Drop the _ARM_ part of the name. We can then introduce a config option like this to aarch64 and other arches using the same name - allowing grep to show them all. Also update the help text to describe the option more completely. Signed-off-by: Andrew Jones <drjones@redhat.com> --- arch/arm/include/asm/kvm_host.h | 4 ++-- arch/arm/kvm/Kconfig | 8 ++++---- 2 files changed, 6 insertions(+), 6 deletions(-)