Ballmer: Microsoft to go after Linux strongholds (ZDNet) [LWN.net]

Ballmer: Microsoft to go after Linux strongholds (ZDNet)

Posted Oct 27, 2005 7:48 UTC (Thu) by ekj (subscriber, #1524)
In reply to: Ballmer: Microsoft to go after Linux strongholds (ZDNet) by nix
Parent article: Ballmer: Microsoft to go after Linux strongholds (ZDNet)

Actually, a massive accumulation parallels trivially and effectively.

In the non-parallell case you've got say one CPU adding up a billion numbers, one after another. This translates to a billion add-operations.

With two CPUs you could let each add up half a billion items, and then at the end add the two results, so total steps is half a billion + 1

With say 1000 CPUs you could let each add up a million items, and then at the end add up all the results, theoretically that part goes fastest with a tree - that way there's only 10 sequential adds. In practice, due to latency and communication-issued simply adding them up at one node may be faster. So you end up with 1,001 million serial additions. That is really freaking close to the theoretical max speedup, 1,001 million is *fairly* close to 1 million.

Now, I don't doubt that much accounting*software* scales badly, but that's a whole different ball of string.

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