We now present some timings. We will vary the parameters raster buffer size and number of threads to see how these affect the results. The total file size of bitmaps (TIFF compressed) written to disk is 287.062 MB. The compression and formatting is done by the sample application but the time required is included in the total time presented below.
Time vs. Concurrent Threads
raster number of number total elapsed time buffer bands of threads 256 MB 6 1 98 secs 256 MB 6 2 74 secs 256 MB 6 3 61 secs 256 MB 6 4 48 secs 256 MB 6 1 98 secs (sanity check to check for OS caching)
What can we conclude from the above data?
Increasing the number of concurrent threads improves performance. Since not all the processing time is multi-threaded and there is some disk IO time one does not get completely proportional reduction in time vs threads.
Time vs. RAM
Since we have 8 GB of RAM (and about 2.5 GB is used by the system) we can increase the raster buffer size. Let's see what effect setting higher raster buffer size gives us.
raster number of number total elapsed time buffer bands of threads 256 MB 6 1 98 secs 512 MB 3 1 96 secs 512 MB 3 1 95 secs (DBS set to 10,000,000) 768 MB 2 1 94 secs 768 MB 2 2 77 secs
Clearly the extra RAM is not helpful for this particular combination of input data and image size/resolution.
raster number of number total elapsed time buffer bands of threads 256 MB 6 4 48 secs Intel Core2 8400 2.66 GHZ 256 MB 6 4 34 secs Intel Core i7 950 3.07 GHz
A faster workstation will result in better throughput.
300 MM Wafer Scale Mask Benchmark