At some point in the history of music, single-instrument compositions gave way to full polyphonic arrangements. Can you imagine it? One day the audiences cheer at your flute solos, the next day they demand not only multiple flutes, but also drums and lyres! Many composers must have thrown down their quills and stormed away. But others, such as Bach andVivaldi, embraced the challenge and created works that continue to draw cheers centuries later.

Modern computing faces a similar challenge. Today’s developers are used to building single-processor applications; they write code for one device, one cache, one memory bank. But as many chip designers have found, the only way to improve processor performance without increasing power consumption is to integrate multiple cores on a single device. To draw maximum performance from such a device, programmers have to understand not only the individual cores but also how they communicate data and access shared memory.

Programming such systems is a tall order, and it’s no surprise that many developers blanch at the thought, stick their heads in the sand, and continue writing single-processor code. However, there can be no question that the future of computing belongs to coders who can design applications for multiprocessor systems. The day will come when students of computer science accept multiprogramming as the norm and look at single-processor coders the way we look at single-instrument composers.

As I write this in mid-2008, it’s clear that day has yet to dawn. The PlayStation 3, despite its incredible capabilities, lags in sales—not only behind Microsoft’s XBox, but behind its predecessor, the PlayStation 2. Why? The reason is simple: There aren’t as many PS3s being sold because there aren’t as many good games for the PS3. There aren’t as many good PS3 games because the Cell is considered too complex to program. So it’s not that the PS3 can’t deliver the power, it’s that the power is perceived as being too hard to harness.

I can’t deny the difficulty, but I hope this book has shown you that the destination is worth the journey. I salute you for summoning the courage to leap with both feet into an entirely foreign computing environment. I hope you’ve maintained enough patience to absorb the details without losing sight of the big picture. Armed with the SDK and the material in this book, I’m certain you’ll be able to compose applications that leave single-processor programs in the dust.