Re: [Qemu-devel] [PATCH] two level table for IO port lookup

[Anthony Liguori]

Brian Wheeler wrote:
> The alpha architecture uses 24 bits for the io port address so this
> patch adds a two level table and puts the IO port data into a
> struct...because sizeof(void *) * 7 * 16777216 is nearly a 1G on my
> workstation.
>
> I've set the alpha target to use a 12/12 split and everything else to
> use 8/8.  
>   

The table lookups really kill performance.  It's probably a better idea 
just to switch to a linear list of IO ports.  There's usually going to 
be a small number of registered IO regions (certainly, less than 100).

Regards,

Anthony Liguori