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KVM: Note down when cpu relax intercepted or pause loop exited 

Noting pause loop exited vcpu or cpu relax intercepted helps in
filtering right candidate to yield. Wrong selection of vcpu;
i.e., a vcpu that just did a pl-exit or cpu relax intercepted may
contribute to performance degradation.

Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com> # on s390x
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Raghavendra K T 2012-07-18 19:07:46 +05:30 committed by Avi Kivity
parent f2a7434731
commit 4c088493c8
2 changed files with 39 additions and 0 deletions
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34
include/linux/kvm_host.h
View File

@ -183,6 +183,18 @@ struct kvm_vcpu {
} async_pf;
#endif
#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
/*
* Cpu relax intercept or pause loop exit optimization
* in_spin_loop: set when a vcpu does a pause loop exit
* or cpu relax intercepted.
* dy_eligible: indicates whether vcpu is eligible for directed yield.
*/
struct {
bool in_spin_loop;
bool dy_eligible;
} spin_loop;
#endif
struct kvm_vcpu_arch arch;
};
@ -898,5 +910,27 @@ static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu)
}
}
#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
static inline void kvm_vcpu_set_in_spin_loop(struct kvm_vcpu *vcpu, bool val)
{
vcpu->spin_loop.in_spin_loop = val;
}
static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val)
{
vcpu->spin_loop.dy_eligible = val;
}
#else /* !CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */
static inline void kvm_vcpu_set_in_spin_loop(struct kvm_vcpu *vcpu, bool val)
{
}
static inline void kvm_vcpu_set_dy_eligible(struct kvm_vcpu *vcpu, bool val)
{
}
#endif /* CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT */
#endif

5
virt/kvm/kvm_main.c
View File

@ -239,6 +239,9 @@ int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
}
vcpu->run = page_address(page);
kvm_vcpu_set_in_spin_loop(vcpu, false);
kvm_vcpu_set_dy_eligible(vcpu, false);
r = kvm_arch_vcpu_init(vcpu);
if (r < 0)
goto fail_free_run;
@ -1585,6 +1588,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
int pass;
int i;
kvm_vcpu_set_in_spin_loop(me, true);
/*
* We boost the priority of a VCPU that is runnable but not
* currently running, because it got preempted by something
@ -1610,6 +1614,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
}
}
}
kvm_vcpu_set_in_spin_loop(me, false);
}
EXPORT_SYMBOL_GPL(kvm_vcpu_on_spin);