Large level 2 caches are usually seen on processors used in powerful back-end servers, such as Intels Xeon chips, but Intel recently increased the L2 cache size on its Pentium III server processors.
Designed for rack-optimized, one-way and two-way servers hosting front-end Web applications in server farms and data centers, the 1.26GHz PIII server processor is available with 512KB of L2 cache, twice the 256KB previously available. The larger cache size is also available on the 1.13GHz PIII processor.
More L2 cache boosts multiprocessor server performance because it reduces the number of times the CPUs need to access the slower DRAM, effectively increasing the memory bandwidth between the processors and the memory system.
I tested the 1.26GHz PIII processors performance using two lp 2000r servers from Hewlett-Packard. The servers had the same hardware components: 1GB of SDRAM, six hard drives and a Gigabit Ethernet adapter. The only difference was that one system had dual PIII 1.26GHz processors with 512KB of L2 cache, while the other had dual PIII processors with 256KB of L2 cache. Both systems were running Windows 2000 Server with IIS 5.0.
Using Ziff Davis Medias WebBench 4.0 with a test suite for static Web content, the server with the faster processors and more cache performed 22 percent better than its rival (see chart, below). However, IT managers will have to factor in the added cost of the bigger on-chip cache when upgrading servers.