On Wed, Jun 29, 2005 at 08:39:15PM -0700, J. Andrew Rogers wrote: > My 32-bit code has built-in support for 10^3 parallelism, and the 64-bit > code gets essentially bottomless parallelism for free (unused bits and > all that). However, as a practical matter I have not used it yet. You > can buy really big shared memory hardware these days for not much money, > and my codes scale pretty nicely if the latency is reasonable.
Unfortunately, shared memory is an expensive mirage to maintain. It doesn't scale very well, due to coherency issuess (if you have r/w intensive operations on a memory block, you have to send lots of signals to and fro until you know it's consistent). This takes lots of time and logic, and is prohibitive for even moderately-sized clusters (IIRC there is no shared memory clusters with 10^3 nodes). No such problems occur with message passing, as it reflects the nature of physical reality. > So I guess you could say the codes have been built to support it, but it > has never been implemented in practice. However, I'll be testing that > before the year is out. Very interesting. Good luck! -- Eugen* Leitl <a href="http://leitl.org";>leitl</a> ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.leitl.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE ------- To unsubscribe, change your address, or temporarily deactivate your subscription, please go to http://v2.listbox.com/member/[EMAIL PROTECTED]
signature.asc
Description: Digital signature
