IntelĀ® MPI Library Reference Manual for Linux* OS
Choose the network interface for MPI communication over TCP-capable network fabrics.
I_MPI_TCP_NETMASK=<arg>
<arg> |
Define the network interface (string parameter) |
<interface_mnemonic> |
Mnemonic of the network interface: ib or eth |
ib |
Use IPoIB* network interface |
eth |
Use Ethernet network interface. This is the default value |
<interface_name> |
Name of the network interface Usually the UNIX* driver name followed by the unit number |
<network_address> |
Network address. Trailing zero bits imply a netmask |
<network_address/ <netmask> |
Network address. The <netmask> value specifies the netmask length |
<list of interfaces> |
A colon separated list of network addresses and interface names |
Set this environment variable to choose the network interface for MPI communication over TCP-capable network fabrics. If you specify a list of interfaces, the first available interface on the node is used for communication.
Use the following setting to select the IP over InfiniBand* (IPoIB) fabric:
I_MPI_TCP_NETMASK=ib
Use the following setting to select the specified network interface for socket communications:
I_MPI_TCP_NETMASK=ib0
Use the following setting to select the specified network for socket communications. This setting implies the 255.255.0.0 netmask:
I_MPI_TCP_NETMASK=192.169.0.0
Use the following setting to select the specified network for socket communications with netmask set explicitly:
I_MPI_TCP_NETMASK=192.169.0.0/24
Use the following setting to select the specified network interfaces for socket communications:
I_MPI_TCP_NETMASK=192.169.0.5/24:ib0:192.169.0.0
Change the size of the TCP socket buffers.
I_MPI_TCP_BUFFER_SIZE=<nbytes>
<nbytes> |
Define the size of the TCP socket buffers |
> 0 |
The default <nbytes> value is equal to default value of the TCP socket buffer size on your Linux system. |
Set this environment variable to manually define the size of the TCP socket buffers. The TCP socket buffer size is restricted by the existing TCP settings on your Linux system.
Use the I_MPI_TCP_BUFFER_SIZE environment variable for tuning your application performance for a given number of processes.
TCP socket buffers of a large size can require more memory for an application with large number of processes. Alternatively, TCP socket buffers of a small size can considerably decrease the bandwidth of each socket connection especially for 10 Gigabit Ethernet and IPoIB (see I_MPI_TCP_NETMASK for details).
Set this environment variable to define a polling mode.
I_MPI_TCP_POLLING_MODE=<mode>
<mode> |
Specify the polling mode |
poll |
The polling mode based on the poll() function. This is the default value |
epoll[:edge] |
The polling mode based on the epoll() function as an edge-triggered interface |
epoll:level |
The polling mode based on the epoll() function as a level-triggered interface |
Set this environment variable to select the polling mode for the tcp fabric.
Use the I_MPI_TCP_POLLING_MODE environment variable for tuning application performance. You can choose the best polling mode on an experimental basis. The best mode depends on the specific application and on the number of processes. The epoll polling mode is a preferable mode in the following situations: