brooks@physics.llnl.gov (Eugene D. Brooks III) (10/02/90)
In article <1990Oct1.200613.635@tera.com> doc@tera.com (Dan Cummings) writes: >Shared memory, in fact, can be >demonstrated to be the only cost effective solution. Would you care to elaborate in detail on this notion?
doc@tera.com (Dan Cummings) (10/03/90)
In <640@llnl.LLNL.GOV> brooks@physics.llnl.gov (Eugene D. Brooks III) writes: >In article <1990Oct1.200613.635@tera.com> doc@tera.com (Dan Cummings) writes: >>Shared memory, in fact, can be >>demonstrated to be the only cost effective solution. >Would you care to elaborate in detail on this notion? Stating that shared memory machines are the only cost effective solution is a sweeping generalization of the same magnitude as Mr. Stein's suggestion that all shared memory machines are technological dinosaurs. Both statements are clearly untrue as general statements. The argument for the cost effectiveness of shared memory architectures is based not on the cost of the machine, but on the life cycle cost of owning and using it. The current application base has been developed in a shared memory programming model. Systems which are used in the near future either have to support a shared memory programming model or force their users to bear the cost of porting their applications. Eventually, it can be argued, the cost of maintaining this old software base will exceed the cost of porting it to a distributed memory programming model. This may be true in the long term. There are applications (Quantum Chromodynamics for example) which may run more cost effectively on distributed memory systems, however a general purpose system is likely to be better accepted if it presents a shared memory programming model. The question is not one of packing maximum computational power into a minimum priced box but one of delivering that computational power to the user in the most cost effective fashion.