Benchmarks Of The Btrfs Space Cache Option

With the 8GB write performance in IOzone, compress again is where the performance really changed compared to space_cache.

The IOzone read performance seemed to drop again, like the Apache results, when using both space_cache and compress, but the results here deviated a lot more with the Linux 2.6.37 kernel than we are used to seeing.

When running one Dbench client there was a nice boost in performance with using space_cache and it was almost to the speed of using the compress mount option. However, when combining compress with space_cache, there really was not much of an added benefit.