Re: [Qemu-devel] [PATCH 0/2] Optimization with AVX2 instruction

[Li, Liang Z]

> On 02/09/2015 07:40, Amit Shah wrote:
> >> The buffer_find_nonzero_offset() will be called to check the zero
> >> page
> >> > during live migration, it's a hot function.
> >> > buffer_find_nonzero_offset() has already been optimized with SSE2
> >> > instructions, for platform that supports AVX2, we can optimize this
> >> > function with AVX2 instructions and achieve about 25% performance
> gain.
> > This should be a good improvement.  I recall Dave and I had a chat
> > about this in the past too.
> >
> > I've not yet reviewed the patchset, but I doubt anyone will have
> > objections.  I'll review this shortly.
> 
> I think we need a better way to enable it than a configure option, however.
> AVX2 machines are rare, and no one would end up using it except perhaps
> Gentoo or other source-based distros.
> 
> Perhaps something like the GCC ifunc attribute?
> Paolo

Thanks for your comments.  ifunc is a good solution, I will send out the v2 
soon.

Liang