Changes between Version 3 and Version 4 of ValidationSummary


Ignore:
Timestamp:
Jun 10, 2008, 9:27:09 AM (16 years ago)
Author:
davea
Comment:

--

Legend:

Unmodified
Added
Removed
Modified
  • ValidationSummary

    v3 v4  
    6363=== Eliminate discrepancies ===
    6464
    65 By selecting the right compiler, compiler options, and math libraries,
    66 it may be possible to eliminate numerical discrepancies.
     65It may be possible to eliminate numerical discrepancies.
     66To do so you'll need to select appropriate compiler, compiler options, and math libraries,
     67and to make sure that your checkpoint files are full precision.
     68
    6769This lets you do bitwise comparison of results.
    6870However, it is difficult and generally reduces the performance of your application.
     
    7678
    7779=== Homogeneous replication ===
    78 There are
    79                         may bound credit
    80                 redundancy
    81                         exact match
    82                                 exact computation
    83                                         sixtrack example: compiler,
    84                                                 compiler options (disable DP hardware),
    85                                                 numerical libraries
    86                                 homogeneous redundancy
    87                                 exact checkpointing
    88                         fuzzy matching
     80
     81With this variant of replication,
     82once an instance of a job has been sent to a host,
     83additional instances are sent only to hosts that are "numerically equivalent"
     84(i.e. that will return bit-identical results).
     85
     86The notion of "numerical equivalence" depends on your application
     87and how it was compiled.
     88BOINC supplies two pre-defined equivalence relations, "coarse" and "fine".
     89Use either of these ("coarse" is preferable, if it's fine enough for your app)
     90or define your own if needed.
     91
     92== Adaptive replication ==
     93
     94This is a refinement of the replication policy.
     95It randomly decides whether to replicate jobs,
     96based on the measured error rate of hosts.
     97If the first instance of a job is sent to a host with a low error rate,
     98then with high probability no further instances will be sent.
     99
     100Adaptive replication is independent of the comparison policy;
     101you can use it with either bitwise comparison,
     102fuzzy comparison, or homogeneous replication.