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Date: Thu, 16 Jul 2009 16:35:11 -0500
From: Anthony Liguori <aliguori@us.ibm.com>
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Subject: Re: [Qemu-devel] [PATCH] introduce on_vcpu
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To: Glauber Costa <glommer@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel@nongnu.org

Glauber Costa wrote:
> On Thu, Jul 16, 2009 at 04:25:12PM -0500, Anthony Liguori wrote:
>   
>> Glauber Costa wrote:
>>     
>>> Yes. Purpose of using curren_env was just to make it look more like qemu-kvm
>>> But I do understand that we'll have to change it anyway for this code to
>>> have any actual value, so I'm fine with using cpu_single_env.
>>>   
>>>       
>> Yeah, if qemu-kvm is introduce another global current CPUState variable,  
>> then the qemu-kvm code has to change :-)
>>
>> Since qemu-kvm keeps a thread id in CPUState, it would make more sense  
>> to check whether gettid() == env->thread_id, no?
>>     
> disagree.
> gettid involves a syscall.

You're prematurely optimizing.  a gettid syscall likely costs around 
150-200 cycles.

>  current_env in qemu-kvm is a TLS variable.
> probably much cheaper.
>
>
>   


-- 
Regards,

Anthony Liguori