i386 vs amd64 - benchmark results
vivek at khera.org
Wed Jul 27 15:52:32 GMT 2005
On Jul 26, 2005, at 1:57 PM, Martin wrote:
> Please notice the memory speed penalties while the
> system is running on amd64 kernel. I would like to
> know what causes this kind of low performance when
> memory is being accessed.
The amd64 memory architecture is NUMA -- that is, depending on how
your RAM is layed out, some of it is faster to access for each
processor. Accessing RAM "local" to the other processor(s) is slower.
There are many subtle issues relating to non-uniform memory access
and how to code programs to take advantage of it (or try to avoid
being bit by it). It is a very hard problem, and the three letters
following my name came to be from researching this issue 11 years
The FreeBSD scheduler and memory allocators are definitely not NUMA
Vivek Khera, Ph.D.
More information about the freebsd-stable