Changes between Version 2 and Version 3 of HomogeneousRedundancy

Timestamp:

Jun 13, 2007, 4:08:59 PM (17 years ago)

Author:

davea

Comment:

--

HomogeneousRedundancy

@@ -13 +13 @@
 BOINC provides a feature called '''homogeneous redundancy''' to handle divergent applications. You can enable it for a project by including the line
 {{{
-<homogeneous_redundancy>1</homogeneous_redundancy>
+<homogeneous_redundancy>N</homogeneous_redundancy>
 }}}
 in the [ProjectConfigFile config.xml] file.
@@ -19 +19 @@
 Alternatively, you can enable it selectively for a single application by setting the `homogeneous_redundancy` field in its database record.
 
-When this feature is enabled, the BOINC scheduler will send results for a given workunit only to hosts with the same operation system name and CPU vendor (i.e., the os_name and p_vendor fields of the host description). For example: if a result has been sent to a host of type (Windows XP, Intel), then other results of that workunit will only be sent to hosts of type (Windows XP, Intel).
+Homogeneous redundancy (HR) divides hosts into 'numerical equivalence classes': two hosts are in the same class if they return identical results for your applications.  The BOINC scheduler will send results for a given workunit only to hosts in the same class; this lets you use strict equality to compare redundant results.
 
-If homogeneous redundancy is enabled, it may be possible to use strict equality to compare redundant results. 
+N specifies the granularity of host classification:
+
+ 0:: Don't user homogeneous redundancy (all hosts are numerically equivalent)
+ 1:: Use a fine-grained classification with 80 classes (4 OS and 20 CPU types).
+ 2:: Use a coarse-grained classification in which there are 4 classes: Windows, Linux, Mac-PPC and Mac-Intel.
+
+The proper classification depends on your application, and how it's compiled (compiler, compiler options, math libraries) on the various platforms.
+WCG reports that the following gcc options (on Linux) cause their apps to produce identical results on all processor types:
+{{{
+-mieee-fp -O3 -fno-rtti -ffor-scope -DNDEBUG
+}}}