SOS7 -- Crystal Ballor a random walk through Mike's brain
Mike Merrill
March 6, 2003
Architecture Matters
This is kind of dated but still relevant…
Now we just put them into racks…
And they might not be this bad… but they might…
Questions What future holds for supercomputing?
more of the same unless we can buy or do something different
not so bad for most but we’ll never solve our toughest problems
What do we want to see? balance, ease, utility, etc...
This is a license to say just about anything ;-)
What makes a supercomputer? It’s really all about application performance
Large Scale Balance Mission Utility Balance of Effort vs. Cost Ease of Use Bandwidth
Compute Efficiency vs. Human Efficiency Ease of use
usable memory bandwidth avoid/hide/manage latency the right compiler and OS support
user’s will do what is easy unless they are like me
something is always getting used at 100% whose time is more important? a person can only write so much code before
death
Programming Abstraction Ditch the explicit communication Ditch the explicit threading/processes in the
“language” Allow for higher level abstractions Make the non-performance critical part (90%) of
the code easier to develop Allow for more optimizations We will never get some of our best scientists to
do some optimizations
Data Structures are Important The other 90% of what you learned from the
“Art of Computer Programming” Sparse Methods are very important Most useful real world data structures have
some linked or random nature to them Future architectures should support these in a
more meaningful way than current and near-term architectures do.
Also need scalable address translation unlike vectors TLBs suck worse
Message Passing vs. Shared Memory this is not the issue the issue is overhead
I happen to like the look and feel of a global address space
My LOC is much less using UPC or CAF still don’t like fixed number of
threads/contexts
Leverage Advances in HW Technology
Not just more of the same ($) Use die area in a more effective way
supporting programming abstraction i.e. support for virtualization of resources
More effective interconnection lower overhead use die area for more effective protocols
Gross View of Resources
Past
RecentPast
NowandNear Term
Capacity and Capability
Capacity Capability
WS Farm High CapacityServer
Large Scale Capability
Conclusions
I am still optimistic about the future When I’ve stopped complaining... then I’ll
go fishing “Ease of use is a myth if you want more
power” “Parallel memory access is the
cornerstone of a computing civilization”
