Changes between Initial Version and Version 1 of AppPlan

Timestamp:

Mar 12, 2008, 2:33:21 PM (16 years ago)

Author:

davea

Comment:

--

AppPlan

@@ +1 @@
+= 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 record (in the server DB) has a character string field '''plan_class'''.
+This identifies the range of processing resources that the application
+requires and is able to use.
+You can define these however you like,
+e.g. "cuda_1_1" apps require a CUDA-enabled GPU,
+"mt32" is a multithreaded app able to use 32 CPUs, etc.
+
+The scheduler is linked with a project-supplied function
+{{{
+bool app_plan(HOST&, char* plan_class, HOST_USAGE&);
+}}}
+The HOST argument describes the host's CPU(s),
+and includes a field 'coprocs' listing its coprocessors.
+
+When called with a particular HOST 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 ncpus;      // #CPUs used by app (may be fractional)
+   double flops;      // estimated FLOPS
+   char opaque[256];  // passed to the app in init_data.xml
+};
+}}}
+
+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 scheduler reply includes, for each app version, an XML encoding of HOST_USAGE.
+
+The client keeps track of coprocessor allocation, i.e. how many instances of each are free.
+It only runs an app if enough instances are available.
+
+The client uses app_version.usage.flops to estimate job completion times.