Changes between Initial Version and Version 1 of HomogeneousAppVersion

Timestamp:

Jun 3, 2011, 3:18:44 PM (13 years ago)

Author:

davea

Comment:

--

HomogeneousAppVersion

@@ +1 @@
+= Homogeneous app version =
+
+BOINC's [HomogeneousRedundancy homogeneous redundancy] (HR) mechanism lets you
+specify that multiple instances of a job must be run on hosts
+whose CPU and OS type are similar,
+to ensure that correct results are identical or
+sufficiently similar to compare.
+
+The HR mechanism doesn't handle GPU app versions;
+e.g. it can't prevent situations where one instance is
+run with a GPU app version and another instance is run with a CPU app version.
+
+We considered adding GPU info to the HR mechanism.
+This turned out to be infeasible.
+
+Instead, Kevin Reed and I propose adding a new mechanism called '''homogeneous app version''' (HAV),
+which ensures that instances of a given job are run using the same app version
+(e.g., Win32/CUDA etc.).
+This can be specified on a per-application basis.
+
+Notes:
+
+ * You can use this together with HR.
+ * Use this only when you're sure that all app versions are correct,
+   since it eliminates cross-checking between versions.
+
+== Implementation notes ==
+
+New DB fields
+
+ * APP::homogeneous_app_version (bool)
+ * WORKUNIT::app_version_id  (int)
+
+The latter is maintained like wu.hr_class:
+it's set when we first dispatch an instance of the job,
+and it's cleared if all instances error out.
+
+Change to best_app_version():
+{{{
+if app.homogeneous_app_version and wu.app_version_id
+   check if this host supports the app version's platform
+   if app version has plan class, check if host can handle it
+   check if we need work for the resource type
+}}}
+
+In some cases this may result in using a non-optional app version;
+e.g. we might use a CUDA 2.0 version for a host capable of running CUDA 2.3.
+So be it.
+
+It's possible that the shared-memory job cache could get clogged up
+with jobs already committed to rare app versions.
+I don't have a plan for dealing with this.