To test the performance in our research group, we have conducted a Benchmark study in selected computers with different resources which have Intel processors. For the study we have used a Hermitian matrix with dimension 7225 and diagonalize the matrix to get eigenvalues and eigenvectors. All the computers have used Windows operating system and compiled using VS-2019. Also Hyper-threading technology has been disabled during the calculations.
In Used Logical Cores column, we have specified the number of cores to use by the programm. Default means the MKL, no specification is given when choosing the number of CPU and other options in this column indicates how many specified cores to be used by the program (i.e. 0-7 means first 8 CPUs are used). CPU usage shows the percentage usage of the total CPUs.
Following table shows the details and performance (time it took to finish calculations) of each computers. The computer number 5 is the resources of the next computer set we are planning to purchase.
There are three questions we do not understand.
1. As it is clear the computer 1 uses 100% CPU during the calculations (it has something to do with i5? processors because all the other computers are either i7 or i9)
2. Computer 1, which is i9 and almost twice physical cores and RAM compared to computer 2, has almost equal perfomance as compupter 2. What is the reason behind this poor performance?
3. Why specifying the number of cores shows total CPU usage to be 100% but perform only nearly as the Default case?
We are planning to purchase a computer number 5. However we'd like to know if this would give 'significantly' better perfomance than the other computers.
Thanks in advance!