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Message-ID: <4FFF979F.8070100@linux.vnet.ibm.com>
Date: Fri, 13 Jul 2012 09:05:59 +0530
From: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
To: Christian Borntraeger <borntraeger@...ibm.com>
CC: "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Marcelo Tosatti <mtosatti@...hat.com>,
Ingo Molnar <mingo@...hat.com>, Avi Kivity <avi@...hat.com>,
Rik van Riel <riel@...hat.com>,
S390 <linux-s390@...r.kernel.org>,
Carsten Otte <cotte@...ibm.com>, KVM <kvm@...r.kernel.org>,
chegu vinod <chegu_vinod@...com>,
"Andrew M. Theurer" <habanero@...ux.vnet.ibm.com>,
LKML <linux-kernel@...r.kernel.org>, X86 <x86@...nel.org>,
Gleb Natapov <gleb@...hat.com>, linux390@...ibm.com,
Srivatsa Vaddagiri <srivatsa.vaddagiri@...il.com>,
Joerg Roedel <joerg.roedel@....com>
Subject: Re: [PATCH RFC V3 2/3] kvm: Note down when cpu relax intercepted
or pause loop exited
On 07/13/2012 01:32 AM, Christian Borntraeger 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.
Yes! I forgot about archs in init function.
How about having
#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
vcpu->ple.cpu_relax_intercepted = false;
vcpu->ple.dy_eligible = false;
#endif
This would solve all the problem.
>>
>> r = kvm_arch_vcpu_init(vcpu);
>> if (r< 0)
>> @@ -1577,6 +1579,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>> int pass;
>> int i;
>>
>> + me->ple.cpu_relax_intercepted = true;
>
> dito
currently vcpu_on_spin is used only by x86 and s390. so if some other
arch in future uses vcpu_on_spin, I believe they also have to enable
CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
what do you think?
otherwise we have to add hook everywhere
>> /*
>> * We boost the priority of a VCPU that is runnable but not
>> * currently running, because it got preempted by something
>> @@ -1602,6 +1605,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>> }
>> }
>> }
>> + me->ple.cpu_relax_intercepted = false;
>
> again.
>
> maybe define static inline access functions in kvm_host.h that are no-ops
> if CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT is not set.
>
--
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