Multicore challenges

GCN Insider: Trends & Technologies that affect the way government does IT

The chips are up: AMD and Intel are heavily promoting dual-core chips, but users might not get all the horsepower the makers claim.

While Advanced Micro Devices Inc. of Sunnyvale, Calif., and Intel Corp. of Santa Clara, Calif., are championing multicore processors, the supercomputing crowd remains ambivalent, at least until these additional cores can be better exploited.

Speaking at the High Performance Computing and Communications Conference held in Newport, R.I., Stephen Wheat, the executive director of Intel's HPC Platform organization, boasted about how a dual-core Intel processor could do 73 percent more work than a single-core model, given the same power.

He said Intel dual-core chips would outsell single cores by year's end, and that four- and eight-core versions were on the way.

But can HPC users actually get at that extra performance? 'I'm concerned [multicore processors] will just be there and nobody will be driven to take advantage of them,' said Douglass Post, head of the Defense Department HPC Modernization Program.

The challenge? The more finely programs are broken into parallel processes (which can run simultaneously on different cores), the more overhead management they need.

'Overhead is a killer. The work to manage that parallelism has to be ... less than the amount of work we're trying to do,' said Thomas Sterling, a faculty associate at CalTech's Center for Advanced Computing Research and a visiting distinguished scientist at Oak Ridge National Laboratory.

'Some of us in the community have been wrestling with these problems for 25 years,' he said. 'You get the feeling [commodity chip designers] are not even aware of them yet. Boy, are they in for a surprise.'

Later, AMD marketing director Margaret Lewis told GCN that the multicore approach works well because most computers run multiple applications simultaneously, which the operating system can divvy up between multiple cores automatically.
So no problem'yet.

But getting multiple cores to run one large application requires concurrent pro- gramming, a demanding discipline now practiced by few.

Eventually, such skills will be needed not only for HPC programs, but enterprise software in general, observers noted.

About the Authors


Joab Jackson is the senior technology editor for Government Computer News.

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