MPI Tuning
Intel® MPI Library includes the
mpitune
tuning utility, which allows you to automatically adjust
Intel MPI Library parameters, such as collective operation algorithms, to your
cluster configuration or application. The tuner iteratively launches a benchmarking
application with different configurations to measure performance and stores the
results of each launch. Based on these results, the tuner generates optimal values
for the parameters that are being tuned.NOTE:
The mpitune
usage
model changed in the 2018 release. Tuning parameters should be specified in
configuration files rather than as command-line options.Configuration File Format
All tuner parameters should be specified in two configuration files, passed to
the tuner with the
--config-file
option. A typical configuration file consists of the main section, specifying
generic options, and search space sections for specific library parameters (for
example, for specific collective operations). Configuration files differ in mode
and dump-file fields only. To comment a line, use the hash symbol #. You can also specify MPI options to simplify
mpitune
usage. MPI options are useful for Intel® MPI Benchmarks
that have special templates for mpitune
located at <
. The templates
require no changes in configuration files to be made.install-dir
>/etc/tune_cfgFor example, to tune the
Bcast
collective algorithm, use the following option:$ mpitune -np 2 -ppn 2 -hosts HOST1 -m analyze -c /path/to/Bcast.cfg
Experienced users can change configuration files to use this option for other
applications.
Output Format
The tuner presents results in a JSON tree view (since the 2019 release), where
the
comm_id=-1
layer is added
automatically for each tree: { "coll=Reduce": { "ppn=2": { "comm_size=2": { "comm_id=-1": { "msg_size=243": { "REDUCE=8": {} }, "msg_size=319": { "REDUCE=11": {} }, "msg_size=8192": { "REDUCE=8": {} }, "msg_size=28383": { "REDUCE=9": {} }, "msg_size=-1": { "REDUCE=1": {} } } } } }}
To add the resulting JSON tree to the library, use the
I_MPI_TUNING
environment variable.Old Output Format
The old output format is only valid for Intel MPI Library 2018 and prior
versions:
I_MPI_ADJUST_BCAST=2:0-0;1:1-64;2:65-509;1:510-8832;3:8833-0
Use the resulting variable value with the application launch to achieve
performance gain.
>
See Also
For details on
mpitune
configuration options, refer to the Developer Reference section Command
Reference > mpitune
.