lamssi - introduction to LAM System Services Interface (SSI)
The SSI in LAM/MPI is used to select one (or more) system services interfaces at
LAM SSI instances are uniquely described in terms of "kinds" (also
referred to as "types") and "modules".
The "kind" refers to which set of system services the SSI instance
will apply to. For example, LAM currently has several kinds: "boot",
"coll", "cr" and "rpi". The "module"
refers to a specific SSI instance of a given kind. Each kind has o
boot modules are used to start the LAM run-time environment (i.e., they provide
the back-end functionality to lamboot
(1)). boot modules are discussed
further in the lamssi_boot(7) man page.
coll modules provide back-end algorithms and functionality for the MPI
collective communications. coll modules are described in lamssi_coll(7).
cr modules provide checkpoint/restart functionality for MPI jobs. See
lamssi_cr(7) for details.
rpi modules provide back-end functionality for MPI point-to-point
communications. rpi modules are detailed in lamssi_rpi(7).
The user can force SSI modules to be verbose by setting the
environment variable before invoking mpirun
or by using the -ssi
command line switch to mpirun
. For example:
- mpirun -ssi ssi_verbose 1 C foo
- Tell the SSI modules to be verbose, and default to sending
their output to stderr.
kind is a "pseudo-kind" in that it is used to
pass parameters to the main SSI meta-glue itself -- not to any particular
kind. It can take many different parameters to format where and how the
verbose output will be sent (note that at least one parameter must be
specified, even if it is an invalid parameter). Any combination of the
following parameters may follow the ssi_verbose
kind (separated by
- Send the verbose output to the syslog.
- Set the syslog output priority to <priority>. Using
this paramter implies the syslog parameter. The default priority is
info (LOG_INFO). Valid <priority> values are: notice
(LOG_NOTICE), info, and debug (LOG_DEBUG).
- Use the ID <id> for the syslog prefix.
- Send the verbose output to stdout.
- Send the verbose output to stderr.
- Send the verbose output to a file in the LAM per-user,
per-node meta information directory (usually located in /tmp). If
<filename> is specified, send the output to the file named
lam-<filename>. If <filename> is not specified, send the
output to the file named lam-ssi.txt.
- Append to the file when sending the verbose output (create
the file if it does not exist). If this parameter is not given, if the
file already exists, it will be overwritten. Using this parameter implies
the file parameter.
- Indicate the specific verbosity level to be used. Although
the specific meaning of the verbosity level is left up to individual SSI
modules, generally negative numbers mean no verbose messages, 0 means a
minimal set of messages, and positive numbers mean more messages (the
greater the positive number, the more output messages will be generated).
If left unspecified any any other ssi_verbose parameters are
specified, the default level of 0 is used.
If multiple parameters are passed in ssi_verbose
, the output will be
directed as implied by all the parameters. If no valid parameters are passed
(e.g., a single invalid parameter is passed), then output will be directed to
stderr by default.
Also note that as with all SSI parameters, all of these values may be passed by
setting the environment variable LAM_SSI_ssi_verbose
. However, parameters passed through "-ssi ssi_verbose"
will take precedence over environment variables.
- mpirun -ssi ssi_verbose 1 C foo
- Since no valid parameters were passed, the verbose output
will be sent to stderr.
- mpirun -ssi ssi_verbose file:output.txt,syslogpri:notice C
- Send the verbose output to both the file lam-output.txt in
the LAM user meta directory as well as to the syslog with a priority of
lamssi_boot(7), lamssi_coll(7), lamssi_cr(7), lamssi_rpi(7), mpirun(1),
lamboot(1), recon(1), lamwipe(1), LAM User's Guide