mirror of https://github.com/BOINC/boinc.git
49 lines
1.9 KiB
HTML
49 lines
1.9 KiB
HTML
<title>Accounting and Result Validation</title>
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<body bgcolor=ffffff>
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<h2>Accounting and Result Validation</h2>
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<p>
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Participants are given <b>credit</b> for the computations performed
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by their hosts.
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These credits are used to generate "leaderboards" of
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individuals, teams, and categories (countries, CPU types, etc.).
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It is
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to be expected that users will explore ways of "cheating", i.e. getting
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undeserved credit.
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<p>
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In principles credit should reflect network transfers and disk
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storage as well as computation.
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However, it's hard to verify these
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activities, so they aren't included in credit.
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<p>
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The core client assigns credit for a completed work unit as a
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function of the CPU time used, and the performance metrics of the CPU
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(discussed later).
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This is sent back to the scheduling server; of
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course, the number can't be trusted in general.
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<p>
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Output files may be wrong.
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This can happen because of hardware
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failures, or because of tampering.
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<p>
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Both problems - credit-cheating and wrong result - can be addressed
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by <b>redundant computing</b> and <b>result validation</b>.
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This means that each workunit is processed at least twice.
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The project back end
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waits until a minimum number of results have been returned, then
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compares the results and decides which are "correct".
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The notion of
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"equality" of results, and the policy for deciding which are correct,
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are project-specific.
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<p>
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The back end then marks correct results as "validated", finds the
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minimum reported credit for the correct results of a given workunit, and
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assigns this amount of credit to all the correct results.
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This ensures
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that as long as a reasonable majority of participants don't falsify
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credit, almost all credit accounting will be correct.
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<p>
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<b>To do</b>: database keeps track of two types of credit: validated
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and unvalidated.
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Users can see the workunits that didn't pass
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validation, or that were given reduced credit.
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