How to improve calculation speed on virtual machines for Exe compiled by Intel Fortran XE2011?

[gqxsun]

We experienced slow calculation speed on virtual machines with use of Exe compiled by Intel Fortran XE2011. The application was for pure numerical calculation which has many do-loops and subroutines. There is no graphics or C or C++ involved. Our local desktop PC: Intel i5-2400 CPU @3.10 GHz, 4 GB RAM, 32 bit operation, Window 7 service pack 1 Our host machine of virtual machines: 8 Core CPU Our virtual machine: Intel i7-920 @2.7 GHz, 2 processor, 1GB Ram, 64 bit operation, window XP service pack 2 The calculation speed of 32xC.exe (32x Exe compiled by Compaq visual Fortran 6.6) on the local PC was slightly faster than the virtual machines. The calculation speeds of 32xC.exe on each virtual machine were not affected by the number of virtual machines in use. The calculation speed of 32xI.exe (32x Exe compiled by Intel Fortran XE2011) was 2 to 3 times faster than 32xC3exe on the local PC. The calculated results are almost identical. We also created 64xI.exe (64x Exe compiled by Intel Fortran XE2011 on the local PC) The optimization option of 'Maximize Speed', 'stack reserve size=10M', 'stack commit size=10M', /Qimf-arch-consistency:true /Qprec were used in Intel XE 2011 for both 32x and 64x application. The calculation speed of 64xI.exe is slightly better than the one of 32xI.exe on virtual NDC machines. But both of them take 30%-500% more time than 32xI.exe on the local PC. May we know what was the reason and how to solve the problem? If you need more information to help us to solve the problem, please let us know. Thank you. Regards, Calbeta

[mecej4]

You have so many combinations here (CVF - IVF, i5 - i7, 32 - 64 bit, native - virtual) that a tabular presentation of you results would make things more readable. It is hard to grasp the issues by reading a line-by-line description of the running times of a number of these combinations.

Unless have a need for /Qprec, you may be able to speed-up the code by choosing other options that facilitate speed.

[jimdempseyatthecove]

>>desktop PC: Intel i5-2400 CPU @3.10 GHz, 4 GB RAM
>>virtual machine: Intel i7-920 @2.7 GHz, 2 processor, 1GB Ram

Might you be having memory starvation issues? (IOW excessive page faults on the i7 920's)

Jim Dempsey

[jeremy_h]

I agree with Jim Dempsey's suggestion. I had trouble with a few compilations and general sluggish executables that moving to a 1.5GB VM fixed.