[gmx-users] Several questions about log file.

[Theodore Si]

Hi,

1. Does "force" in the R E A L   C Y C L E   A N D   T I M E   A C C O U 
N T I N G table mean the time spent on short-range force calculation?
2. Does "Comm. coord" mean the communication of atom positions when 
calculating short-range force interaction?
3. What forces are waited and communicated in "Wait + Comm. F"?

Each node of our cluster has two Intel(R) Xeon(R) CPU E5-2670 0 @ 
2.60GHz, each has 8 cores.

When we are using 2 nodes, that is 2nodes * 2 cpus * 8 cores = 32 cores, 
we will be
Using 32 MPI processes
Using 1 OpenMP thread per MPI proces
and
Comm. coord.          24    1      19200       1.483 92.327     1.0
1.483s are spent on the coordinate communication


When we are using 32 nodes, that is 32nodes * 2 cpus * 8 cores = 32 
cores, we will be
Using 512 MPI processes
Using 1 OpenMP thread per MPI proces
and
Comm. coord.         384    1      19200       2.094 2086.377     5.2
2.094s are spent on the coordinate communication

4. Why the time spent on communication of coordinate doesn't scale up as 
the cores are increasing?

BR,
Theo