Benchmark (III) RHEL4
After installing additional RAM into the workstation and updating the operating system to RHE4 we then ran the benchmarks again. The dual 1.6 GB Opteron workstation would not properly support SATA drives under RHE4 so we changed to ATA drives but did not use them in a RAID configuration.
1. Nothing is written to disk in the above benchmarks so the change in hard drives should not make a difference.
2. Doubling the pixel resolution should increase rasterization time by 4X. It only increases 2.5X from test #1 to test #2. This implies that a considerable amount of compute time is used for other than pure raster operations such as exploding the data and checking/repairing polygons.
Raster, Format and Compress
Dual 1.6 GB Opteron with 7.4GB RAM, gdsriplib v1.04, RHE4, threads = 4, DBS = 4 million
1. Adding a second buffer (so that rasterization can simultaneously occur with compression/writing) improves throughput by about 1.25 except when the buffers are so large that the system begins to swap.
1. Test 9 & 10 use identical parameters but timing differs by about 5%. This was found due to the "state" of the system at the time the run begins.
2. Increasing the buffer size beyond a certain value does not necessarily improve throughput - if enough RAM is available one should use two smaller buffers. In this benchmark it is better to use dual 1024 MB buffers ( test#11 ) than a single 2048 buffer ( test#12 ) or dual 2048 buffers ( test#13 ).