TIMEF() exhibits different behaviour in Linux and Windows

I have spent some time today trying to sort out a bottleneck in my code and been using timef() from the portability library.

I have both linux (Ubuntu 16) and Windows (7) versions of the compiler - both 2017 - update 5.  There is only one version of the code and the compiler switches for the two OSs are as good as the same.

It appears to me that the linux version is rounding to an integer. Here is a snip of the debug output for linux

 kgsave=   2.000000     move to record=   0.000000     sizegrid=   1.000000     kgload=   1.000000   
 kgsave=   2.000000     move to record=   0.000000     sizegrid=   0.000000     kgload=   2.000000   
 kgsave=   1.000000     move to record=   0.000000     sizegrid=   1.000000     kgload=   1.000000   
 kgsave=   1.000000     move to record=   0.000000     sizegrid=   1.000000     kgload=   1.000000   

and here is the same thing for Windows (a virtual machine on the linux box)

 kgsave=  0.8750000     move to record=   0.000000     sizegrid=  0.4687500E-01 kgload=  0.7343750    
 kgsave=  0.7656250     move to record=   0.000000     sizegrid=  0.4687500E-01 kgload=  0.4062500    
 kgsave=  0.7968750     move to record=   0.000000     sizegrid=  0.3125000E-01 kgload=  0.5312500    
 kgsave=  0.8437500     move to record=   0.000000     sizegrid=  0.6250000E-01 kgload=  0.7343750   

There are some efficiencies in the windows libraries calling the Win API versus the Xorg/Motif calls in linux which explains the faster times but not the precision differences.

The numbers were just created with timer(1)=timef() before the call to the subroutine and timer(2)=timef() after then printing out timer(2)-timer(1). Timer declared as a selected_real_kind(15) array.

Am I doing something wrong or is this problem real?

Cheers

Kim