Re: [PATCH RFC V3 2/3] kvm: Note down when cpu relax interceptedor pause loop exited
From: Raghavendra K T
Date: Mon Jul 16 2012 - 03:40:23 EST
On 07/13/2012 07:24 PM, Srikar Dronamraju wrote:
On 12/07/12 21:18, Raghavendra K T wrote:
+#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
[...]
+ struct {
+ bool cpu_relax_intercepted;
+ bool dy_eligible;
+ } ple;
+#endif
[...]
}
vcpu->run = page_address(page);
+ vcpu->ple.cpu_relax_intercepted = false;
+ vcpu->ple.dy_eligible = false;
This struct is only defined if CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT is set, but here it
is always accessed. Will break on !x86&& !s390.
How about moving this struct definition outside the CONFIG.
i.e it would be available by default.
If any arch cares to use vcpu_on_spin(), they would get the benefit by
default.
This would avoid all the CONFIG magic that we would have to do
otherwise.
Okay, after discussing with Christian,
- even if ppc uses vcpu_on spin we will still be left with ia64 (though
broken currently) and arm (is on way).
- those who want to opt-out of this optimization but still wish to use
vcpu_spin, we have flexibility.
So with that in mind I am spinning V4 with
CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT. Let us see how it goes.
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