Version 25 (modified by 13 years ago) (diff) | ,
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Application planning
Application planning is a mechanism that lets the scheduler decide, using project-supplied logic:
- whether an application should run on a particular host;
- what resources it will use;
- how fast it is expected to run.
It works as follows.
An app version has an associated plan_class: a character string, possibly empty. See how to specify an app version's plan class.
The scheduler is linked with a function
bool app_plan(SCHEDULER_REQUEST &sreq, char* plan_class, HOST_USAGE&);
The sreq argument describes the host. It contains:
- in sreq.host field, a description of the host's hardware, including:
- In p_vendor and p_model, the processor type
- In p_features, the processor features (e.g., fpu tsc pae nx sse sse2 mmx)
- In m_nbytes, the amount of RAM
- in sreq.coprocs, a list of the hosts's coprocessors.
- in core_client_version, the client's version number in MMmmRR form.
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 { double ncudas; // number of NVIDIA GPUs used double natis; // number of ATI GPUs used double gpu_ram; // max amount of GPU RAM used double avg_ncpus; // avg #CPUs used by app (may be fractional) double max_ncpus; // max #CPUs used (not currently used for anything) double projected_flops; // an estimate of the actual FLOPS. // used to select versions, so make it higher for the preferred version double peak_flops; // the peak FLOPS of the devices to be used 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 projected_flops is greatest.
If gpu_ram is nonzero, the BOINC client (6.10.25+) won't start the app unless that much RAM is available on the allocated GPU.
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_customize.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.
- 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).
- sse3
- A CPU app that requires the SSE3 CPU feature.
- vbox32
- An app that runs in a 32-bit VirtualBox VM
- vbox64
- An app that runs in a 64-bit VirtualBox VM
... and a number of GPU plan classes.
Note: plan classes containing the substrings 'nvidia', 'cuda', and 'ati' are reserved for GPU applications.