Re: [Qemu-devel] [PATCH] introduce on_vcpu

[Anthony Liguori]

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