Influence of L2 Cache Size on Conroe Processors Performance
As new Pentium E2000 processors emerged in the market, we got three types of dual-core processors on Core micro-architecture equipped with a shared L2 cache of 4MB, 2MB and 1MB capacity. Therefore it would be extremely interesting to see how the size of L2 cache affects the processor performance in widespread applications. To check this out we compared the performance of Pentium E2160 processor working at 1.8GHz frequency and featuring 1MB L2 cache against that of a Core 2 Duo E4300 processor with 1.8GHz frequency and 2MB L2 cache and against that of a hypothetical Core 2 Duo processors running at 1.8GHz and featuring 4MB L2 cache. Since there is no processor like that supporting 800MHz bus and 4MB L2 cache in Intel Core 2 Duo lineup, we used an Intel Core 2 Extreme X6800 processor with reduced clock frequency multiplier of 9x and bus speed set at 800MHz.
So, the diagrams below will show the performance of CPUs on Core micro-architecture that worked at 1.8GHz speed, supported 800MHz bus and featuring 1MB, 2MB and 4MB L2 cache onboard.
During video encoding the size of L2 cache doesn’t affect the performance that much. The results of CPUs with 4MB and 1MB cache differ by about 3-4%.
The same situation takes place during audio encoding. However, this time the performance difference approaches 5% and is primarily noticed when we move from 2MB L2 cache to only 1MB.
Microsoft Office Word 2007 loses a lot of speed when the L2 cache gets smaller. Moreover, if the CPU with a 2MB L2 cache is only 5% slower than its counterpart with a 4MB L2 cache, then further L2 cache size reduction results in a 15-16% performance drop compared with the “fully-fledged” CPU.