Re: [Qemu-devel] [PATCH] exec: optimize phys_page_set_level

[Richard Henderson]

On 05/21/2015 06:19 AM, Paolo Bonzini wrote:
> memcpy is faster than struct assignment, which copies each bitfield
> individually.  Arguably a compiler bug, but memcpy is super-special
> cased anyway so what could go wrong?

The compiler has the option of doing the copy either way.  Any way to actually 
show that the small memcpy is faster?  That's one of those things where I'm 
sure there's a cost calculation that said per member was better.



r~