* [PATCH 0/3] KVM_MAX_VCPUS related changes
@ 2013-09-14 12:10 Andrew Jones
2013-09-14 12:10 ` [PATCH 1/3] arm: kvm: clamp NR_VCPUS to MAX_VCPUS Andrew Jones
` (2 more replies)
0 siblings, 3 replies; 17+ messages in thread
From: Andrew Jones @ 2013-09-14 12:10 UTC (permalink / raw)
To: linux-arm-kernel
Andrew Jones (3):
arm: kvm: clamp NR_VCPUS to MAX_VCPUS
arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS
aarch64: kvm: introduce CONFIG_KVM_MAX_VCPUS
arch/arm/include/asm/kvm_host.h | 4 ++--
arch/arm/kvm/Kconfig | 8 ++++----
arch/arm/kvm/arm.c | 2 +-
arch/arm64/include/asm/kvm_host.h | 7 ++++++-
arch/arm64/kvm/Kconfig | 11 +++++++++++
5 files changed, 24 insertions(+), 8 deletions(-)
--
1.8.1.4
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 1/3] arm: kvm: clamp NR_VCPUS to MAX_VCPUS 2013-09-14 12:10 [PATCH 0/3] KVM_MAX_VCPUS related changes Andrew Jones @ 2013-09-14 12:10 ` Andrew Jones 2013-09-14 12:14 ` Alexander Graf 2013-09-14 12:10 ` [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS Andrew Jones 2013-09-14 12:10 ` [PATCH 3/3] aarch64: kvm: introduce CONFIG_KVM_MAX_VCPUS Andrew Jones 2 siblings, 1 reply; 17+ messages in thread From: Andrew Jones @ 2013-09-14 12:10 UTC (permalink / raw) To: linux-arm-kernel Signed-off-by: Andrew Jones <drjones@redhat.com> --- arch/arm/kvm/arm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c index 741f66a2edbd7..9ebf8ac3a12ff 100644 --- a/arch/arm/kvm/arm.c +++ b/arch/arm/kvm/arm.c @@ -201,7 +201,7 @@ int kvm_dev_ioctl_check_extension(long ext) r = 1; break; case KVM_CAP_NR_VCPUS: - r = num_online_cpus(); + r = min(num_online_cpus(), KVM_MAX_VCPUS); break; case KVM_CAP_MAX_VCPUS: r = KVM_MAX_VCPUS; -- 1.8.1.4 ^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 1/3] arm: kvm: clamp NR_VCPUS to MAX_VCPUS 2013-09-14 12:10 ` [PATCH 1/3] arm: kvm: clamp NR_VCPUS to MAX_VCPUS Andrew Jones @ 2013-09-14 12:14 ` Alexander Graf 2013-09-14 12:22 ` Marc Zyngier 2013-09-14 12:23 ` Andrew Jones 0 siblings, 2 replies; 17+ messages in thread From: Alexander Graf @ 2013-09-14 12:14 UTC (permalink / raw) To: linux-arm-kernel Am 14.09.2013 um 07:10 schrieb Andrew Jones <drjones@redhat.com>: > Signed-off-by: Andrew Jones <drjones@redhat.com> > --- > arch/arm/kvm/arm.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index 741f66a2edbd7..9ebf8ac3a12ff 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -201,7 +201,7 @@ int kvm_dev_ioctl_check_extension(long ext) > r = 1; > break; > case KVM_CAP_NR_VCPUS: > - r = num_online_cpus(); > + r = min(num_online_cpus(), KVM_MAX_VCPUS); Is there any real reason to prohibit overcommit? Alex > break; > case KVM_CAP_MAX_VCPUS: > r = KVM_MAX_VCPUS; > -- > 1.8.1.4 > > _______________________________________________ > kvmarm mailing list > kvmarm at lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 1/3] arm: kvm: clamp NR_VCPUS to MAX_VCPUS 2013-09-14 12:14 ` Alexander Graf @ 2013-09-14 12:22 ` Marc Zyngier 2013-09-14 12:23 ` Andrew Jones 1 sibling, 0 replies; 17+ messages in thread From: Marc Zyngier @ 2013-09-14 12:22 UTC (permalink / raw) To: linux-arm-kernel On 2013-09-14 13:14, Alexander Graf wrote: > Am 14.09.2013 um 07:10 schrieb Andrew Jones <drjones@redhat.com>: > >> Signed-off-by: Andrew Jones <drjones@redhat.com> >> --- >> arch/arm/kvm/arm.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c >> index 741f66a2edbd7..9ebf8ac3a12ff 100644 >> --- a/arch/arm/kvm/arm.c >> +++ b/arch/arm/kvm/arm.c >> @@ -201,7 +201,7 @@ int kvm_dev_ioctl_check_extension(long ext) >> r = 1; >> break; >> case KVM_CAP_NR_VCPUS: >> - r = num_online_cpus(); >> + r = min(num_online_cpus(), KVM_MAX_VCPUS); > > Is there any real reason to prohibit overcommit? I don't think this affects overcommit. This is the "recommended" limit, and you can still go up to KVM_MAX_CPUS. M. -- Fast, cheap, reliable. Pick two. ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 1/3] arm: kvm: clamp NR_VCPUS to MAX_VCPUS 2013-09-14 12:14 ` Alexander Graf 2013-09-14 12:22 ` Marc Zyngier @ 2013-09-14 12:23 ` Andrew Jones 1 sibling, 0 replies; 17+ messages in thread From: Andrew Jones @ 2013-09-14 12:23 UTC (permalink / raw) To: linux-arm-kernel On Sat, Sep 14, 2013 at 07:14:02AM -0500, Alexander Graf wrote: > > > Am 14.09.2013 um 07:10 schrieb Andrew Jones <drjones@redhat.com>: > > > Signed-off-by: Andrew Jones <drjones@redhat.com> > > --- > > arch/arm/kvm/arm.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > > index 741f66a2edbd7..9ebf8ac3a12ff 100644 > > --- a/arch/arm/kvm/arm.c > > +++ b/arch/arm/kvm/arm.c > > @@ -201,7 +201,7 @@ int kvm_dev_ioctl_check_extension(long ext) > > r = 1; > > break; > > case KVM_CAP_NR_VCPUS: > > - r = num_online_cpus(); > > + r = min(num_online_cpus(), KVM_MAX_VCPUS); > > Is there any real reason to prohibit overcommit? This doesn't prohibit it. Users can attempt to configure anything they'd like, but only selections KVM_MAX_VCPUS and below will work. drew > > Alex > > > break; > > case KVM_CAP_MAX_VCPUS: > > r = KVM_MAX_VCPUS; > > -- > > 1.8.1.4 > > > > _______________________________________________ > > kvmarm mailing list > > kvmarm at lists.cs.columbia.edu > > https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS 2013-09-14 12:10 [PATCH 0/3] KVM_MAX_VCPUS related changes Andrew Jones 2013-09-14 12:10 ` [PATCH 1/3] arm: kvm: clamp NR_VCPUS to MAX_VCPUS Andrew Jones @ 2013-09-14 12:10 ` Andrew Jones 2013-09-15 9:30 ` Gleb Natapov ` (2 more replies) 2013-09-14 12:10 ` [PATCH 3/3] aarch64: kvm: introduce CONFIG_KVM_MAX_VCPUS Andrew Jones 2 siblings, 3 replies; 17+ messages in thread From: Andrew Jones @ 2013-09-14 12:10 UTC (permalink / raw) To: linux-arm-kernel 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. config KVM_ARM_VGIC bool "KVM support for Virtual GIC" -- 1.8.1.4 ^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS 2013-09-14 12:10 ` [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS Andrew Jones @ 2013-09-15 9:30 ` Gleb Natapov 2013-09-16 8:09 ` Marc Zyngier 2013-09-17 21:42 ` Christoffer Dall 2013-09-24 14:09 ` [PATCH v2] " Andrew Jones 2 siblings, 1 reply; 17+ messages in thread From: Gleb Natapov @ 2013-09-15 9:30 UTC (permalink / raw) To: linux-arm-kernel 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. ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS 2013-09-15 9:30 ` Gleb Natapov @ 2013-09-16 8:09 ` Marc Zyngier 2013-09-16 8:32 ` Gleb Natapov 0 siblings, 1 reply; 17+ messages in thread From: Marc Zyngier @ 2013-09-16 8:09 UTC (permalink / raw) To: linux-arm-kernel 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. -- Jazz is not dead. It just smells funny... ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS 2013-09-16 8:09 ` Marc Zyngier @ 2013-09-16 8:32 ` Gleb Natapov 2013-09-16 8:49 ` Marc Zyngier 0 siblings, 1 reply; 17+ messages in thread From: Gleb Natapov @ 2013-09-16 8:32 UTC (permalink / raw) To: linux-arm-kernel 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. ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS 2013-09-16 8:32 ` Gleb Natapov @ 2013-09-16 8:49 ` Marc Zyngier 0 siblings, 0 replies; 17+ messages in thread From: Marc Zyngier @ 2013-09-16 8:49 UTC (permalink / raw) To: linux-arm-kernel 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. -- Jazz is not dead. It just smells funny... ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS 2013-09-14 12:10 ` [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS Andrew Jones 2013-09-15 9:30 ` Gleb Natapov @ 2013-09-17 21:42 ` Christoffer Dall 2013-09-24 14:09 ` [PATCH v2] " Andrew Jones 2 siblings, 0 replies; 17+ messages in thread From: Christoffer Dall @ 2013-09-17 21:42 UTC (permalink / raw) To: linux-arm-kernel 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). -- Christoffer ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH v2] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS 2013-09-14 12:10 ` [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS Andrew Jones 2013-09-15 9:30 ` Gleb Natapov 2013-09-17 21:42 ` Christoffer Dall @ 2013-09-24 14:09 ` Andrew Jones 2013-09-25 19:31 ` Christoffer Dall 2 siblings, 1 reply; 17+ messages in thread From: Andrew Jones @ 2013-09-24 14:09 UTC (permalink / raw) To: linux-arm-kernel 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> --- v2: reword help text some more --- arch/arm/include/asm/kvm_host.h | 4 ++-- arch/arm/kvm/Kconfig | 9 +++++---- 2 files changed, 7 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..8e56ccf45edce 100644 --- a/arch/arm/kvm/Kconfig +++ b/arch/arm/kvm/Kconfig @@ -40,16 +40,17 @@ 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. Choosing a lower number decreases + the size of the VM data structure. This number may also be + increased. config KVM_ARM_VGIC bool "KVM support for Virtual GIC" -- 1.8.1.4 ^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH v2] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS 2013-09-24 14:09 ` [PATCH v2] " Andrew Jones @ 2013-09-25 19:31 ` Christoffer Dall 2013-09-26 7:54 ` Andrew Jones 0 siblings, 1 reply; 17+ messages in thread From: Christoffer Dall @ 2013-09-25 19:31 UTC (permalink / raw) To: linux-arm-kernel On Tue, Sep 24, 2013 at 04:09:28PM +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> > > --- > v2: reword help text some more > --- > arch/arm/include/asm/kvm_host.h | 4 ++-- > arch/arm/kvm/Kconfig | 9 +++++---- > 2 files changed, 7 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..8e56ccf45edce 100644 > --- a/arch/arm/kvm/Kconfig > +++ b/arch/arm/kvm/Kconfig > @@ -40,16 +40,17 @@ 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. Choosing a lower number decreases > + the size of the VM data structure. This number may also be > + increased. > Maybe I'm being forgetful, but what do you mean by "This number may also be increased" ? -Christoffer ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH v2] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS 2013-09-25 19:31 ` Christoffer Dall @ 2013-09-26 7:54 ` Andrew Jones 0 siblings, 0 replies; 17+ messages in thread From: Andrew Jones @ 2013-09-26 7:54 UTC (permalink / raw) To: linux-arm-kernel On Wed, Sep 25, 2013 at 12:31:27PM -0700, Christoffer Dall wrote: > On Tue, Sep 24, 2013 at 04:09:28PM +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> > > > > --- > > v2: reword help text some more > > --- > > arch/arm/include/asm/kvm_host.h | 4 ++-- > > arch/arm/kvm/Kconfig | 9 +++++---- > > 2 files changed, 7 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..8e56ccf45edce 100644 > > --- a/arch/arm/kvm/Kconfig > > +++ b/arch/arm/kvm/Kconfig > > @@ -40,16 +40,17 @@ 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. Choosing a lower number decreases > > + the size of the VM data structure. This number may also be > > + increased. > > > Maybe I'm being forgetful, but what do you mean by "This number may also > be increased" ? Originally I was proposing we write 'increase for scalability testing', as would be the purpose on the x86 side. However, you suggested it can be increased for other purposes, although you didn't mention what. I just dropped the 'scalability testing' to allow users to fill the blank in themselves. If it doesn't really make sense on arm to increase this beyond what hardware supports, then we can drop the 'increase' completely and add a range 1 <same-as-default> to the Kconfig entry instead. drew ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 3/3] aarch64: kvm: introduce CONFIG_KVM_MAX_VCPUS 2013-09-14 12:10 [PATCH 0/3] KVM_MAX_VCPUS related changes Andrew Jones 2013-09-14 12:10 ` [PATCH 1/3] arm: kvm: clamp NR_VCPUS to MAX_VCPUS Andrew Jones 2013-09-14 12:10 ` [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS Andrew Jones @ 2013-09-14 12:10 ` Andrew Jones 2013-09-17 21:34 ` Christoffer Dall 2 siblings, 1 reply; 17+ messages in thread From: Andrew Jones @ 2013-09-14 12:10 UTC (permalink / raw) To: linux-arm-kernel 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 + 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 ^ permalink raw reply related [flat|nested] 17+ messages in thread
* [PATCH 3/3] aarch64: kvm: introduce CONFIG_KVM_MAX_VCPUS 2013-09-14 12:10 ` [PATCH 3/3] aarch64: kvm: introduce CONFIG_KVM_MAX_VCPUS Andrew Jones @ 2013-09-17 21:34 ` Christoffer Dall 2013-09-18 6:21 ` Gleb Natapov 0 siblings, 1 reply; 17+ messages in thread From: Christoffer Dall @ 2013-09-17 21:34 UTC (permalink / raw) To: linux-arm-kernel 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 > -- Christoffer ^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 3/3] aarch64: kvm: introduce CONFIG_KVM_MAX_VCPUS 2013-09-17 21:34 ` Christoffer Dall @ 2013-09-18 6:21 ` Gleb Natapov 0 siblings, 0 replies; 17+ messages in thread From: Gleb Natapov @ 2013-09-18 6:21 UTC (permalink / raw) To: linux-arm-kernel 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. ^ permalink raw reply [flat|nested] 17+ messages in thread
end of thread, other threads:[~2013-09-26 7:54 UTC | newest] Thread overview: 17+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2013-09-14 12:10 [PATCH 0/3] KVM_MAX_VCPUS related changes Andrew Jones 2013-09-14 12:10 ` [PATCH 1/3] arm: kvm: clamp NR_VCPUS to MAX_VCPUS Andrew Jones 2013-09-14 12:14 ` Alexander Graf 2013-09-14 12:22 ` Marc Zyngier 2013-09-14 12:23 ` Andrew Jones 2013-09-14 12:10 ` [PATCH 2/3] arm32: kvm: rename CONFIG_KVM_ARM_MAX_VCPUS Andrew Jones 2013-09-15 9:30 ` Gleb Natapov 2013-09-16 8:09 ` Marc Zyngier 2013-09-16 8:32 ` Gleb Natapov 2013-09-16 8:49 ` Marc Zyngier 2013-09-17 21:42 ` Christoffer Dall 2013-09-24 14:09 ` [PATCH v2] " Andrew Jones 2013-09-25 19:31 ` Christoffer Dall 2013-09-26 7:54 ` Andrew Jones 2013-09-14 12:10 ` [PATCH 3/3] aarch64: kvm: introduce CONFIG_KVM_MAX_VCPUS Andrew Jones 2013-09-17 21:34 ` Christoffer Dall 2013-09-18 6:21 ` Gleb Natapov
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