Parallelism at HotPar 2010

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The Contrarian View: Do We Really Need Parallelism?

A polemical talk accompanying a position paper by Karu Sankaralingam of UW-Madison suggested there is no parallelism problem today and that parallelizing applications for the multicore future is not necessary. A number of “synergistic” trends were outlined, including the rise of the cloud, and the emergence of multicore in support of the thesis. The premise being that hardware no longer drives software, and that multicore hardware is not everywhere. Thus we shall not all be parallel programmers, as parallelism is not necessary for the majority of cases. In a client/server world, updated for the cloud and connected devices, there is abundant concurrency at the server but precious little everywhere else.

Thus the vast majority of developers can use simple client Javascript and Ruby on Rails or Django where productivity is key, in order to raise the level of abstraction. While a tiny number (“1271”) of guru developers at the lowest levels of the software stack, operating systems and databases, can churn out increasingly complex concurrent code for the multicore server loads of the future. The iconoclastic talk understandably caused a minor ruckus in the room. There were no less than seven questioners lined up to challenge or pillory the speaker, who took it all in stride. It was mentioned by others that though chip throughput performance follows Moore’s Law, latency does not. Dr. Patterson noted that current devices already feature multiple cores, and he bet Karu that a future iPhone will sport 8-10 application programmable cores in a few years with developers taking advantage of their data parallelism in Objective C.

Another criticism leveled was that by narrowly defining parallelism to cases where it is already established and nowhere else, the thesis does not make a novel point or consider that new areas benefiting from parallelism are likely to emerge. For example, how many processors does it take to power the Holodeck? Some academics in the audience were “shocked” at how unimaginative the speaker was. That being said, it takes a certain gumption to come before the altar of the church of parallelism and utter blasphemy to the assembled worshipers. Karu was jovial, even taking off an outer article of clothing to reveal a flame retardant shirt before the question and answer period commenced.

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