int score_runtime_resource(void);
void score_runtime_usage(void);
score_runtime_resource() is a callback function that must be
implemented by a user program or runtime library. It is used to check
user-specified resources of scrun(1) SCore options.
score_runtime_usage() is a callback function that must be
implemented to print the usage of the runtime.
scrun(1) invokes the user program specified on its
command line on the host where scrun was executed, in order to
parse a user-specified resource request and to check if the request is valid
or not. This is performed in the score_initialize() function
where the score_runtime_resource() function (written by the
programmer) is called so the runtime can check the resource request. If the
function returns a non-zero value, then user program invocation is aborted,
otherwise scrun attempts to login to SCore-D.
After successfully logging in to SCore-D, SCore-D forks and
execs the user program on the allocated cluster node(s). Here,
score_initialize() is called again on each node.
All runtime libraries must call the score_initialize() function
prior to accessing variables defined in <score.h> and
to communicate via the PM library. Inside
score_initialize(), all necessary information passed by
SCore-D is retrieved and initialized in PM contexts, so that a user program
can communicate with other nodes.
#include <score.h>
void my_runtime_initialize(int argc, char **argv) {
score_initialize(argc, argv);
/* score_initialize() does not return, when this program is
invoked on a local host. */
/* When a user program is invoked on one or more cluster nodes,
the program can reach this point, and the runtime can
initialize itself. */
}
score_get_resource_request() function:
#include <score_resource.h>
int score_runtime_resource(void) {
scoreResourceRequest *rsrc = score_get_resource_request();
:
return( 0 );
}
Also, there is a set of
resource macros to constrain the resource request.
score_become_idle() and
score_become_busy() functions let SCore-D know the
running state of a user process. If a user process becomes
idle, even if the program is actually waiting in a busy-wait
loop, it is preferable to call
score_become_idle(), and score_become_busy()
when the process is about to become busy. By
reporting the status of a user process correctly, SCore-D can
detect the global state of user parallel processes, and
SCore-D tries to de-schedule a process if the process is in global
idle, or tries to kill the process if it is assumed to be globally
terminated, possibly because of deadlock. The timing of message
consumption by the pmReleaseReceiveBuffer() and the
calling of those functions is very important.
void idle_loop( void ) {
caddr_t buf;
size_t size
while( pmReceive( score_pmnet[0], &buf, &size ) == ENOBUF ) {
score_become_idle();
}
score_become_busy();
process_received_message( buf, size );
pmReleaseReceiveBuffer( score_pmnet[0] );
return;
}
As in the above example, the score_become_busy()
function must be called before the consumption of the
received message by calling
pmReleaseReceiveBuffer(). If violated, a user
parallel process can be de-scheduled or killed by SCore-D
erroneously.
#include <score_usage.h>
void score_runtime_usage(void) {
score_separate_usage("My-Runtime");
score_print_usage("magic", "NN", "magic number");
:
}
This sample code for displaying language runtime usage produces the
following message:
-- My-Runtime -- magic=NN magic number
scrun(1),
score_initialize(3),
score_runtime_resource(3),
score_become_idle(3),
score_become_busy(3),
resource macros