Tuesday, 2 December 2008

HPC and parallel processing - 2 fave quotes

From HPC wire
Posted by Michael Feldman - November 27 @ 9:04AM

Clever software can make even great hardware humble. D-Wave CTO Geordie Rose, the panel's quantum computing advocate, argued that new algorithms can have a much bigger payoff than more powerful silicon. He noted that using Pollard's rho algorithm from 1977, it would take 12 years to factor a 90-digit number on a modern-day 400 teraflop Blue Gene supercomputer. But using the newer quadratic seive algorithm, it would take just 3 years to perform the same operation on a 1977 Apple II computer. When you consider the multi-million dollar investment that went into the Blue Gene supercomputer compared to the probable investment that went into developing the new algorithm, you can get some sense of the industry's misplaced priorities.

From Slashdot ..
By acidrain (35064) on Thursday March 22 2007, @08:00AM (#18441773)

Look guys. There is no multi-processing silver bullet. It isn't even such a hard problem, *if you stop trying to solve it at such a low level*. Break your application into separate pieces that, *don't need to communicate very often.* Then this is the same kind of problem scalable websites like Google, MySpace, Hotmail and so on, have already, just without having to factor in the reliability issues. Finer grained multi-threading just leads to deadlocks and is really hard to debug. If you *really must* render the same sphere on 100 processors at the same time, then you need the speed of a custom coded solution. But you don't so let it go. The main loop of your program will be just fine as a single threaded implementation, 1 processor will do, and farm the 10% code / 90 % heavy lifting out in big clean chunks to other processors. If you find yourself writing some bizzare multi-threaded message passing system so that you can have 100s of threads all modifying the same live object model at the same time -- you are fucked, just forget about it 'cause you will never be able to debug that one killer bug that you know is going to get you right as you go to ship.

Pure genius from the net

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