HP-MPI Version 1.0 for Windows Release Note

HP-MPI V1.0 for Windows Release Note

Known Problems and Workarounds

• Selecting specific machine resources for the task that calls mpirun causes failures. Due to

a defect in the Microsoft CCS job scheduler, assigning specific resources to an allocation

causes further CCS API calls from that allocation to fail. It is possible to select specific

machine resources to a job allocation. However, users should not specify specific resources

for the task that invokes mpirun. Under the Processors tab of the Task Properties

dialog box, be sure to retain the default setting of "Use any available processors on any

nodes" and do not choose "Select nodes required for this task".

• Currently, the CCS scheduler does not allow for multiple tasks to be run on specifically

selected nodes. The implication is that for the time being, you can only 'block schedule'

ranks for an MPI job.

• The Fortran interface provided in HP-MPI assumes a calling convention of C by reference.

That is, function names are not decorated as _function@bytes, arguments are passed by

reference, string length arguments are passed by value after the other arguments, and the

caller cleans the stack. This is not compatible with Compaq Visual Fortran (CVF) or other

compilers using the STDCALL calling convention for Fortran routines (e.g. /iface:cvf in

Intel Fortran). The STDCALL calling convention decorates the function names, passes

string lengths by value directly after the string, and has the callee clean the stack.

• Current IB drivers (Voltaire 2.1) have a performance issue with Winsock Direct (WSD). If

the user of the application does not have Domain Admin privileges, using the IB network

address will result in standard TCP/IPoIB performance. Domain Admin privileges are

currently required to enable WSD when using the IB network address. This does not

affect IBAL protocol. Contact Voltaire for the fix (which is unavailable at the time of this

release).

• Current IB drivers (Voltaire 2.1) will suffer a loss of performance after sending message

sizes of 4065 bytes to 4128 bytes when using WSD. Any messages sent afterwards will

perform at about half the bandwidth that they performed at before the 4065-4128 byte

message was sent. This does not affect IBAL protocol. Contact Voltaire for the fix (which is

unavailable at the time of this release).

• Voltaire 32-bit IBAL drivers have an issue when calling LoadLibrary on the IBAL.dll. So,

at this time, IBAL does not work for 32-bit applications.