Message-ID: <4ABF25F8.3050209@redhat.com>
Date: Sun, 27 Sep 2009 10:44:40 +0200
From: Avi Kivity <avi@redhat.com>
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To: Zachary Amsden <zamsden@redhat.com>
CC: Marcelo Tosatti <mtosatti@redhat.com>, kvm@vger.kernel.org,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH: kvm 3/6] Fix hotadd of CPUs for KVM.
References: <1253762945-5750-1-git-send-email-zamsden@redhat.com> <1253762945-5750-2-git-send-email-zamsden@redhat.com> <1253762945-5750-3-git-send-email-zamsden@redhat.com> <20090924155224.GC14102@amt.cnet> <4ABBD76D.6050308@redhat.com>
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On 09/24/2009 11:32 PM, Zachary Amsden wrote:
> On 09/24/2009 05:52 AM, Marcelo Tosatti wrote:
>>
>>> +static __cpuinit int vmx_cpu_hotadd(int cpu)
>>> +{
>>> +    struct vmcs *vmcs;
>>> +
>>> +    if (per_cpu(vmxarea, cpu))
>>> +        return 0;
>>> +
>>> +    vmcs = alloc_vmcs_cpu(cpu);
>>> +    if (!vmcs)
>>> +        return -ENOMEM;
>>> +
>>> +    per_cpu(vmxarea, cpu) = vmcs;
>>> +
>>> +    return 0;
>>> +}
>> Have to free in __cpuexit?
>>
>> Is it too wasteful to allocate statically with 
>> DEFINE_PER_CPU_PAGE_ALIGNED?
>
> Unfortunately, I think it is.  The VMX / SVM structures are quite 
> large, and we can have a lot of potential CPUs.

I think percpu is only allocated when the cpu is online (it would still 
be wasteful if the modules were loaded but unused).

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

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