Re: [RFC] Documentation about unaligned memory access

Arne Georg Gleditsch
2007-11-23T09:46:39Z

dean gaudet <dean@arctic.org> writes:
> on AMD x86 pre-family 10h the boundary is 8 bytes, and on fam 10h it's 16
> bytes. the penalty is a mere 3 cycles if an access crosses the specified
> boundary.

Worth noting though, is that atomic accesses that cross cache lines on
an Opteron system is going to lock down the Hypertransport fabric for
you during the operation -- which is obviously not so nice.

--
Arne.