Testbed and methods
Benchmarks were performed on a system equipped with:
- PhenomII 940 CPU (4 cores @ 3.0 GHz, 1.8 GHz Northbridge and 6 MB L3 cache)
- 8 GB DDR2-800 DRAM (in unganged mode)
- Asus M4A78 Pro motherboard (AMD 780G + SB700 chipset)
- 4x 500 GB hard disks (1x WD Green, 3x Seagate Barracuda) in AHCI mode, configured in software RAID10 "near" layout
- S.O. CentOS 6.5 x64
I timed the compression and decompression of two different datasets:
- a tar file containing an uncompressed CentOS 6.5 minimal install / (root) image (/boot was excluded)
- the tar file containing Linux 3.14.1 stable kernel
In order to avoid any influence by the disk subsystem, I moved both dataset in the RAM-backed /dev/shm directory (you can think about it as a RAMDISK).
When possible, I tried to separate single-threaded results from multi-threaded ones. However, it appear that 7-zip has no thread-selection options, and by default it spawn as many threads as the hardware threads the CPU provide. So I marked 7-zip results with an asterisk (*)
Many compressors expose some tuning – for example, selecting “-1” generally means a faster (but less effective) compression that “-9”. I experimented with these flags also, where applicable.