SCore-D User Manual (1)

a.out [-score option_string] arg1 arg2 ... argn
Here let us assume a.out is an executable file linked with SCore-D runtime library. When invoking a "SCore-D aware" program, resulting process on a local host is called Front End Process (FEP), and the runtime library of FEP tries to connect specified SCore-D server host and then it forks a parallel process on a cluster. User code runs in parallel on the cluster. After the connection with SCore-D is established, all the standard output of the user parallel program are passes to the FEP and output as the standard output of the FEP. The standard error is also output as well. SIGINT (^C), SIGTSTP (^Z) and SIGCONT (fg UNIX shell command) are caught by the FEP, and SCore-D controls the FEP and corresponding user parallel process to follow the action required. Thus SCore-D gives an illusion that FEP is an entity of user's parallel program execution. During the initialization of the runtime library, the command argument is scanned, and the library assumes that the argument next to the keyword -score is SCore option string. The rest of the arguments are passed to user program, a.out.

Options in the option string is separated by comma (,) or blank. When each option is separated by blanks, entire option string must be quoted. The -score keyword and the next option string can be placed anywhere in the command arguments. Each option setting consists of keyword and value. Like shell einvironment variable, the keyword and associated value are separated by an equal (=) symbol character.

Option string is searched from left to right. If there are two or more options having the same keyword, leftmost one is taken. After searching the option string, SCore tries to get the other option strings from shell environment variable named SCORE_OPTIONS and SCORED_OPTIONS.

Effective options can vary depending on which library is linked with the executable file. In general, communication library and language runtime library are required to be linked. Such libraries may have different options from the others. Thus, the options listed in this section is a minimum set.

SCore takes the value of shell environment variable environ as a option string. Its format is the same as the one in command argument. The option string spcified in the environment variable can contain the default option.
This option setting is replaced by the environment variable name and its value. SCore does not pass environment variables of invoked process to the processes spawned.
The program prints option setting information, and then exits.
The program first prints current option setting, and then starts its execution.

The number of host nodes required to run the program is specified by number_of_nodes option. Note that the specified number is taken as a request, and the actual number of allocated host number may be different.
The hostname is assumed to be SCore-D server host, and the runtime library tries to connect to the host to submit a job.

When a user parallel process terminates, SCore-D output some statistics information on the execution of the parallel process.
In addition to the stat option, statistics information on individual nodes is also output.
Invoke a real-time activity monitor of a user parallel process. Currently two monitor programs, loadmonitor and loadmonitor3d, are available. The loadmonitor is a simple X-client program and displays a two dimensional image.

window exsample of

And the loadmonitor3d is a OpenGL (MESA and GLUT) application and displayes a three dimensional image. By draggin mouse on the window, user can rotate (left button), enlarge or shrink (middle button) the image.

window exsample of

On both monitoring programs, red cell or bar indicates busy node, and blue cell or bar indicates idle node. To use one of the above monitoring programs, user must set a proper PATH environment for the program(s).

If the debug options is specified, and SCore-D detects an exceptional signal, then SCore-D tries to invoke a GDB and let it attach to the user program. DISPLAY shell environment variable is expected to be set properly, so that xterm under which GDB runs can display a window on your host.

Termination (Deadlock) Detection
SCore-D monitors activities of user parallel processes. When SCore-D detects a explicit termination due to a deadlock, SCore-D kills the terminated user parallel process.
User program binary file
User program binary files must be readable by SCore-D. This is because, when a user submit a job to SCore-D, firstly SCore-D copies user program binary file to SCore-D temporary directory.
User-ID and Current Working Directory
SCore-D fork() and exec() user programs, and set user-ID and change current working directory. When users are using NFS (Network File System) or AFS (Andrew File System), the PWD environment variable is not set properly under some shells. In this case SCore-D fails to spawn user processes. To avoid this, use tcsh or others which set the PWD environment variable properly. Further, because of protection, user-ID must be larger than or equal to 100. SCore-D also fails to spawn user processes, if it has no ROOT permission.

Option string specified in the command argument is analyzed, then the runtime library tries to get option string from this shell environment variable also.
Next to SCORE_OPTIONS einvironment variable, this environment variable is analized.


SCore User Manual

Real World Computing Partnership
Parallel Distributed System Software Tsukuba Laboratory

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