I’m using this older synthetic test because it actually breaks out some tests into single, dual and four thread tests within the CPU benchmark. Let’s look at the overall CPU score, then a single-threaded, dual-threaded and four-threaded benchmark.
In theory, even a heavily CPU oriented benchmark won’t see perfect scaling unless it all fits in the L2 cache. These tests fit nicely in the 8MB L3 cache of the Nehalem architecture, but are probably a big large for the 256KB per core L2 cache. This is a pretty old benchmark, so take the results with a lump of salt.
Hmm. There’s only a 4% difference in the overall CPU score.That’s what you’d expect, maybe a little worse. But if we look at individualtests, we see a nearly 6% difference in the File Decompression single threadedtest – better than you’d expect from the clock rate difference. Curiously,there’s almost no difference in the dual-threaded test, yet an expected 4%difference in the four-thread test.
Remember, this is a very old benchmark by today's standards. Cache hierarchies and sizes have changed, but I used this test because the more current PCMark Vantage doesn't break down tasks this way.