Intel’s Atom CPU flexes multithreading muscle
Intel’s new sub-2.5 watt Atom CPU (codenamed Silverthorne) is showing it can run two process threads at the same time better than competing processors. The Atom’s hyperthreading feature (in-order SMT) allows the single-core processor to be seen as two logical processors by an operating system. When both processors are used whenever more than one task is being performed in the computer, substantial gains in performance can be made.
According to these slides presented at IDF on page 17, the Atom is showing an whopping 39% performance gain on SPECint_rate2000 when running two process threads at a mere 17% increase in power consumption. Hexus.net found that the Atom’s hyperthreading feature allowed it to improve CINEBENCH 9.5 performance by more than 53%. It should be noted that SPECint_rate2000 doesn’t really stress the memory subsystem so one would expect the SPECint_rate2006 gains on Atom hyperthreading to be lower. However it’s not really practical to expect a small mobile or embedded device to have 4 Gigabytes of RAM with high memory bandwidth.
Some like Linus Torvalds criticized these Hyperthreading results because he feels that good Hyperthreading performance could be viewed in the glass-half-empty perspective of poor single-threaded performance. I disagree with him because having a second processor is very beneficial to a computer especially when a single process locks up. Modern compilers also have the auto-parallelization features that will try to take advantage of the second processor for single-threaded applications.
The closest competitor for the Intel Atom is Via’s Isaiah processor. Recent benchmarks from Eeepcnew.de seem to have indicated that Via’s C7 Isaiah processor performs approximately 39% better on raw integer performance and approximately 3.5% better on raw floating point performance. While the Isaiah processor performs well and has reasonable power consumption for a desktop and some larger notebooks, it consumes nearly 10 times more power than the Intel Atom. Furthermore, the results from Eeepcnew.de are for single threading so once you factor in SMT performance gains, the Atom may actually perform better than the Isaiah.