Application planning

Application planning is a mechanism that lets the scheduler decide, using project-supplied logic, whether an application is able to run on a particular host, and if so what resources it will use and how fast it will run. It works as follows.

An app version has an associated plan_class: a character string, possibly empty. The plan class is encoded in the app version's directory name, as used by update_versions.

The scheduler is linked with a function

bool app_plan(SCHEDULER_REQUEST &sreq, char* plan_class, HOST_USAGE&);

The sreq argument contains:

• in sreq.host field, a description of the host's processors and memory
• in sreq.global_prefs field, the user's global preferences
• in sreq.coprocs, a list of the hosts's coprocessors.

When called with a particular SCHEDULER_REQUEST and plan class, the function returns true if the host's resources are sufficient for apps of that class. If true, it populates the HOST_USAGE structure:

struct HOST_USAGE {
   COPROCS coprocs;   // coprocessors used by the app (name and count)
   double avg_ncpus;  // avg #CPUs used by app (may be fractional)
   double max_ncpus;  // max #CPUs used (relevant if user changes prefs later)
   double flops;      // estimated FLOPS
   char cmdline[256]; // passed to the app as a cmdline argument;
                      // this can be used, e.g. to control the # of threads used
};

When deciding whether to send a job to a host, the scheduler examines all latest-version app_versions for the platform, calls app_plan() for each, and selects the one for which flops is greatest. The client uses flops to estimate job completion times.

You are free to define your own set of plan classes, and to link your own app_plan() function with the scheduler. The BOINC scheduler comes with a default app_plan() (in sched/sched_plan.cpp). This defines the following plan classes:

mt

An application that can use anywhere from 1 to 64 threads, and whose speedup with N CPUs is .95N. It is passed a command-line argument --nthreads N.

cuda

A CUDA application that requires 254MB of GPU RAM, and that uses .5% as many CPU FLOPS as GPU FLOPS.

nci

A non-CPU-intensive application that uses 1% of a CPU (this will cause the BOINC client 6.7+ to run it at non-idle priority).

Notes

• The server code that estimates completion times currently doesn't know about multiprocessors or coprocessors.