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Message-ID: <20130714141818.GD11772@redhat.com>
Date: Sun, 14 Jul 2013 17:18:18 +0300
From: Gleb Natapov <gleb@...hat.com>
To: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
Cc: mingo@...hat.com, jeremy@...p.org, x86@...nel.org,
konrad.wilk@...cle.com, hpa@...or.com, pbonzini@...hat.com,
linux-doc@...r.kernel.org, habanero@...ux.vnet.ibm.com,
xen-devel@...ts.xensource.com, peterz@...radead.org,
mtosatti@...hat.com, stefano.stabellini@...citrix.com,
andi@...stfloor.org, attilio.rao@...rix.com, ouyang@...pitt.edu,
gregkh@...e.de, agraf@...e.de, chegu_vinod@...com,
torvalds@...ux-foundation.org, avi.kivity@...il.com,
tglx@...utronix.de, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org, stephan.diestelhorst@....com,
riel@...hat.com, drjones@...hat.com,
virtualization@...ts.linux-foundation.org,
srivatsa.vaddagiri@...il.com
Subject: Re: [PATCH RFC V10 18/18] kvm hypervisor: Add directed yield in vcpu
block path
On Mon, Jun 24, 2013 at 06:14:15PM +0530, Raghavendra K T wrote:
> kvm hypervisor: Add directed yield in vcpu block path
>
> From: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
>
> We use the improved PLE handler logic in vcpu block patch for
> scheduling rather than plain schedule, so that we can make
> intelligent decisions.
>
What kind of improvement this provides? Doesn't it screw up our pause
exit heuristics?
> Signed-off-by: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
> ---
> arch/ia64/include/asm/kvm_host.h | 5 +++++
> arch/powerpc/include/asm/kvm_host.h | 5 +++++
> arch/s390/include/asm/kvm_host.h | 5 +++++
> arch/x86/include/asm/kvm_host.h | 2 +-
> arch/x86/kvm/x86.c | 8 ++++++++
> include/linux/kvm_host.h | 2 +-
> virt/kvm/kvm_main.c | 6 ++++--
This miss some arches.
> 7 files changed, 29 insertions(+), 4 deletions(-)
>
> diff --git a/arch/ia64/include/asm/kvm_host.h b/arch/ia64/include/asm/kvm_host.h
> index 989dd3f..999ab15 100644
> --- a/arch/ia64/include/asm/kvm_host.h
> +++ b/arch/ia64/include/asm/kvm_host.h
> @@ -595,6 +595,11 @@ int kvm_emulate_halt(struct kvm_vcpu *vcpu);
> int kvm_pal_emul(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run);
> void kvm_sal_emul(struct kvm_vcpu *vcpu);
>
> +static inline void kvm_do_schedule(struct kvm_vcpu *vcpu)
> +{
> + schedule();
> +}
> +
> #define __KVM_HAVE_ARCH_VM_ALLOC 1
> struct kvm *kvm_arch_alloc_vm(void);
> void kvm_arch_free_vm(struct kvm *kvm);
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index af326cd..1aeecc0 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -628,4 +628,9 @@ struct kvm_vcpu_arch {
> #define __KVM_HAVE_ARCH_WQP
> #define __KVM_HAVE_CREATE_DEVICE
>
> +static inline void kvm_do_schedule(struct kvm_vcpu *vcpu)
> +{
> + schedule();
> +}
> +
> #endif /* __POWERPC_KVM_HOST_H__ */
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index 16bd5d1..db09a56 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -266,4 +266,9 @@ struct kvm_arch{
> };
>
> extern int sie64a(struct kvm_s390_sie_block *, u64 *);
> +static inline void kvm_do_schedule(struct kvm_vcpu *vcpu)
> +{
> + schedule();
> +}
> +
> #endif
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 95702de..72ff791 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1042,5 +1042,5 @@ int kvm_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info);
> int kvm_pmu_read_pmc(struct kvm_vcpu *vcpu, unsigned pmc, u64 *data);
> void kvm_handle_pmu_event(struct kvm_vcpu *vcpu);
> void kvm_deliver_pmi(struct kvm_vcpu *vcpu);
> -
> +void kvm_do_schedule(struct kvm_vcpu *vcpu);
> #endif /* _ASM_X86_KVM_HOST_H */
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b963c86..84a4eb2 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -7281,6 +7281,14 @@ bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu)
> kvm_x86_ops->interrupt_allowed(vcpu);
> }
>
> +void kvm_do_schedule(struct kvm_vcpu *vcpu)
> +{
> + /* We try to yield to a kicked vcpu else do a schedule */
> + if (kvm_vcpu_on_spin(vcpu) <= 0)
> + schedule();
> +}
> +EXPORT_SYMBOL_GPL(kvm_do_schedule);
> +
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
> EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_page_fault);
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index f0eea07..39efc18 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -565,7 +565,7 @@ void mark_page_dirty_in_slot(struct kvm *kvm, struct kvm_memory_slot *memslot,
> void kvm_vcpu_block(struct kvm_vcpu *vcpu);
> void kvm_vcpu_kick(struct kvm_vcpu *vcpu);
> bool kvm_vcpu_yield_to(struct kvm_vcpu *target);
> -void kvm_vcpu_on_spin(struct kvm_vcpu *vcpu);
> +bool kvm_vcpu_on_spin(struct kvm_vcpu *vcpu);
> void kvm_resched(struct kvm_vcpu *vcpu);
> void kvm_load_guest_fpu(struct kvm_vcpu *vcpu);
> void kvm_put_guest_fpu(struct kvm_vcpu *vcpu);
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 302681c..8387247 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1685,7 +1685,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
> if (signal_pending(current))
> break;
>
> - schedule();
> + kvm_do_schedule(vcpu);
> }
>
> finish_wait(&vcpu->wq, &wait);
> @@ -1786,7 +1786,7 @@ bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu)
> }
> #endif
>
> -void kvm_vcpu_on_spin(struct kvm_vcpu *me)
> +bool kvm_vcpu_on_spin(struct kvm_vcpu *me)
> {
> struct kvm *kvm = me->kvm;
> struct kvm_vcpu *vcpu;
> @@ -1835,6 +1835,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>
> /* Ensure vcpu is not eligible during next spinloop */
> kvm_vcpu_set_dy_eligible(me, false);
> +
> + return yielded;
> }
> EXPORT_SYMBOL_GPL(kvm_vcpu_on_spin);
>
--
Gleb.
--
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