tim <TimJ@internet.com> wrote:
| Alan Crowe wrote:
| > Tim Bradshaw <firstname.lastname@example.org> writes:
| >> Do implementations typically have *any* free tag bits (and if so, why)?
| > Doesn't the move to 64 bits change this? If I were thinking about
| > designing a new language I would be tempted to say it was 64 bit only,
| > with 48 bit addresses and the luxury of 16 tag bits.
| Hmmmm... we are using about 36 bits now in large systems, and memory sizes
| are going up by roughly 1 bit per 12 months. So 48 bits will run out in
| only 12 years.
Sooner than that. Large SGI Altix systems already need 44 physical
address bits to be able to address main system RAM (yes, they can
put ~14 TB of global cache-coherent RAM on their largest ccNUMA boxes).
Rob Warnock <email@example.com>
627 26th Avenue <URL:http://rpw3.org/>
San Mateo, CA 94403 (650)572-2607