I found the JPEG lossless speed is 200% slow on the same brand DELL machine with different CPU. The test is done by using the IPP sample program jpegview.exe. From the about menu, I can see the dispatch DLL is different between tow machines. One uses the v8 version, another uses t7 version. Both machines CPUs are Xeon CPU, but the CPU are detected as different types.
Here is the test data. The low performance machine actually has more cores than fast one. How could the JPEG performance are so different?
Fast DELL 490 2 CPU 4 cores
Intel Xeon CPU 5140 @ 2.33GHz
EM64T Family 6 Model 15 Stepping 6, GenuineIntel
752x753x3 8 bitsJpeg lossless load timing: 18561.96 us
Slow DELL 490 2 CPU 8 cores
Intel Xeon CPU 3.20GHz
EM64T Family 15 Model 6 Stepping 4, GenuineIntel
752x753x3 8 bitsJpeg lossless load timing: 48474.34 us
This mean we do have highly optimized code for V8 library (tuned by hands) and do not have this for T7 library (meaning compiler optimization only used in T7 library for some functions used in lossless JPEG).
JPEG_EXTENDED mode. Why do we have set param.huffman_opt = 1? However in baseline mode I have to set param.huffman_opt = 0 to make 8 bits lossy compression work.