Re: [PATCH kvm-unit-tests 2/4] Introduce a C++ wrapper for the kvm APIs

Avi Kivity
2010-11-28T09:54:30Z

On 11/28/2010 11:50 AM, Michael S. Tsirkin wrote:
> > >
> > >Another problem is that there seem to be two memory allocations and a
> > >copy here, apparently just to simplify error handling. It might be fine
> > >for this test but won't scale for when performance matters.
> >
> > When it matters, we can fix it. I don't see msr read/write becoming
> > a hot path.
>
> It will be very painful to fix it.

Why? One copy is necessary (it's due to the bad kvm API), but we can
avoid the others.

In any case the data will be copied by the kernel.

>
> >
> > The compiler should optimize it away completely.
>
> Should as opposed to does. Want me to try a simple test?

Please.

> > There's been a lot
> > of work in gcc on that.
> >
> > About compile times, I don't care much.
>
> I do. You will too when we have codebase that can be built as fast as
> we commit things, so buildbot breaks.
> This is common in C++ based projects.

If kvm-unit-tests.git takes to long to compile, I'll be very happy.

--
error compiling committee.c: too many arguments to function