Execution speeds on CVF6.6 vs Intel VF9

[S_W_]

Last week Idownloaded the evaluation version of Intel VF for testing and compared it to CVF 6.6. I was runing these tests on an AMD3400 box and also on a Pentium M (2.13GHz) laptop. The F90 code is about 12000 lines and isintensive floating point calculations.Consistently the CVFexe ran 40-50% faster than the Intel VF exe.

I started with a CVF project and converted it to a IntelVF project following the S. Lionel's porting suggestions. No other chnages were made in the IVF project properties.

Here are the CVF settings:

/compile_only /nologo /real_size:64 /warn:nofileopt /fast /module:"Release/" /object:"Release/"

[This is a release version setting, using double precision for all real numbers, optimizing for a 'blend', full optimizations]

Here are the IVF settings:

/nologo /Zi /Od /real_size:64 /iface:cvf /module:"$(INTDIR)/" /object:"$(INTDIR)/" /traceback /check:bounds /libs:static /dbglibs /c

Any suggestions on improving the performance of the IVF code?

[Steven_L_Intel1]

You're comparing a CVF release build to an IVF debug build. No optimization, bounds checking and other slowdowns. Try a Release configuration first. /O3 /QxB /assume:noaccuracy_sensitive would be switches to try. (You can't use /fast on a Pentium M.) Turn off bounds checking.

[TimP]

/O3 /Zi ought to perform OK, but I got a customer report today that /Zi reduces performance significantly, even when /O is specified. As Steve pointed out, the Pentium M often runs faster on CVF code, or with the /QxB option (optimize for Pentium M), than with more usual ifort options.

[S_W_]

Oops - I copied the debug settings rather than the release settings: Here are the correct Intel VF release settings taht the comparisons were based on:

/nologo /GB /align:dcommons /align:sequence /iface:cvf /module:"$(INTDIR)/" /object:"$(INTDIR)/" /c

Scott

[S_W_]

Oops! I pasted the settings for the debug setting - here are the correct IVF release settings I used:

/nologo /GB /real_size:64 /align:dcommons /align:sequence /iface:cvf /module:"$(INTDIR)/" /object:"$(INTDIR)/" /c

Appreciate any further ideas, Thanks, Scott

[Steven_L_Intel1]

Try the options I suggested. And if it doesn't help, please submit the program with explanation to Intel Premier Support. We're very interested in such cases.

Remove /GB.