boinc/doc/validate.php

<?php
require_once("docutil.php");
page_head("Validation");
echo "
<p>
In BOINC, the process of <b>validation</b> does two things:
<ul>
<li> it compares redundant results
and decides which ones are to be considered correct;
<li> it decides how much credit to grant to each correct result.
</ul>
<p>
A <b>validator</b> is a daemon program.
You must supply a validator for each application in your project,
and include it in the &lt;daemons&gt; section of your
<a href=configuration.php>project configuration file</a>.

<p>
Depending on various factors,
you may be able to use a standard validator that comes with BOINC,
or you may have to develop a custom validator.
<ul>
<li>
If your application generates exactly matching results
(either because it does no floating-point arithmetic, or because you use
<a href=homogeneous_redundancy.php>homogeneous redundancy</a>)
then you can the 'sample bitwise validator' (see below).
<li>
If you are using BOINC for 'desktop grid' computing
(i.e. you trust all the participating hosts)
then you can use the 'sample trivial validator' (see below).
<li>
Otherwise, you'll need to develop a custom validator for your application.
BOINC supplies a <a href=validate_high.php>high-level validator framework</a>
in which you plug in three short application-specific functions.
This is sufficient for more projects.
If you need more control over the validation process,
you can use BOINC's <a href=validate_low.php>low-level validator framework</a>.
</ul>

<p>
Two standard validators are supplied:
<ul>
<li>
The <b>sample_bitwise_validator</b> requires a strict majority,
and regards results as equivalent only if they agree byte for byte.
<li>
The <b>sample_trivial_validator</b>
regards any two results as equivalent if their CPU time
exceeds a given minimum.
</ul>
<p>

<h3>Command-line arguments</h3>
A validator (either standard or custom) has the following command-line arguments:
";
list_start();
list_item("-app appname", "Name of the application");
list_item("[ -one_pass_N_WU N ]", "Validate at most N WUs, then exit");
list_item("[ -one_pass ]", "Make one pass through WU table, then exit");
list_item("[ -mod n i ]",
    "Process only WUs with (id mod n) == i.
    This option lets you run multiple instances of the validator
    for increased performance."
);
list_end();
page_tail();
?>