eldavojohn writes: Multicore (think tens or hundreds of cores) will come at a price for current operating systems. A team at MIT found that as they approached 48 cores their operating system slowed down. After activating more and more cores in their simulation, a sort of memory leak occurred whereby data had to remain in memory as long as a core might need it in its calculations. But the good news is that in their paper (PDF), they showed that for at least several years Linux should be able to keep up with chip enhancements in the multicore realm. To handle multiple cores, Linux keeps a counter of which cores are working on the data. As a core starts to work on a piece of data, Linux increments the number. When the core is done, Linux decrements the number. As the core count approached 48, the amount of actual work decreased and Linux spent more time managing counters. But the team found that 'Slightly rewriting the Linux code so that each core kept a local count, which was only occasionally synchronized with those of the other cores, greatly improved the system's overall performance.' The researchers caution that as the number of cores skyrockets, operating systems will have to be completely redesigned to handle managing these cores and SMP. After reviewing the paper, one researcher is confident Linux will remain viable for five to eight years without need for a major redesign.
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