Re-install of Visual Fortran compiler 11.1

[DnO]

My retirement hobby is developing an algorithm using 11.1 and Microsoft Visual Studio 2008. I "timed" it (and competing methods) on my 4GHz CPU and would like to time them on a 3 GHz CPU, which would then go into an upcoming article. I bought a refurbished 3 GHz PC but can't seem to install the 11.1 compiler on it. It says it is "reading existing licenses" and goes no further. Am I making a mistake or is this illegal? I bought the CD from Intel for $756.67 on July 21, 2009 by credit card. I could just forget the 3GHz data, but I think the paper would have a better chance of being accepted, if included. Any suggestions appreciated.

[mecej4]

My suggestion: just install the 11.1 runtime on the 3 GHZ PC (the one without a license for Ifort 11), if you have or can find a version Ifort 11 installer. Transfer the EXE (and any data files needed) that you build on your 4 GHZ PC to the other and run/time the EXE.

Note that run times depend on the instruction set, cache size, etc., and that the CPU frequency is not the only factor that affects run times.

Instead, you could download, install and use the current version of Intel Fortran, which does not require a license file. See this post by Ron Green.

[DnO]

Thanks mecej4,

Will follow that last link to try and download the current compiler version into my 3 GHz PC ( I have nothing to lose).

If I can ask one more question, is it possible to time an algorithm on the 4 GHz CPU using only ONE of the four cores? Since a square root takes 4-5 floats (adds) on my quad core, I'm curious to see how many floats a square root would take on one core. But I'm not sure how many single-core CPUs are still in use.

[mecej4 · Accepted solution]

The speed of an algorithm will be affected not only by the CPU speed, but also on the number of threads (many current CPUs allow two threads per core). Vector (SIMD) instructions may be provided in the CPU to enable performing 4, 8 or 16 simultaneous square root evaluations within a single thread.

Using a modern compiler with suitable options, you can compile, run and time your algorithm with different numbers of simultaneous threads, different instruction sets, and so on.

Note that you will need to obtain and install a recent version of Visual Studio as a prerequisite for the OneAPI package, and the OS version needs to be be recent enough to allow installation of OneAPI.

Which CPUs are you running your tests on? What operating systems are they running?

[DnO]

Right now, the only CPU I can run my tests on is my 2017 custom-made PC with a 4 GHz 4-core i7-6700K and Win10/64bit.  Sadly, after I got that PC in 2017, I got rid of my previous custom-made PC, which had a 3 GHz CPU and was running IVF 11.1, MVS/2008 and Vista I believe. The only other PC I have now is a refurbished online-purchased one, a Dell with a 3 GHz Core-2-Duo and Win10/64, which the 11.1 CD won't install on. 

Will check into getting MVS into the Dell, but may have to be satisfied with the accuracy estimates, operation counts, and 4 GHz timing estimates of all the algorithms (using default settings).  

[DnO]

@mecej4, Thanks for all the food for thought about compilers and the observations about the square root operation that I had been grappling with.