LAM SSI - introduction to LAM System Services Interface (SSI)
The SSI in LAM/MPI is used to select one (or more) system services
interfaces at run-time.
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
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
LAM_SSI_ssi_verbose 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.
The ssi_verbose 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 before
invoking mpirun. 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 foo
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