mirror of https://github.com/BOINC/boinc.git
52 lines
1.8 KiB
HTML
52 lines
1.8 KiB
HTML
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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
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performed by their hosts.
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These credits are used to generate "leaderboards"
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of individuals, teams, and categories (countries, CPU types, etc.).
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It is to be expected that users will explore ways of "cheating",
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i.e. getting undeserved credit.
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<p>
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In principles credit should reflect network transfers and
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disk storage as well as computation.
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However, it's hard to verify these activities,
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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
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as a function of the CPU time used,
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and the performance metrics of the CPU (discussed later).
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This is sent back to the scheduling server;
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of 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 failures,
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or because of tampering.
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<p>
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Both problems - credit-cheating and wrong result -
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can be addressed by <b>redundant computing</b>
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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 waits until a minimum number
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of results have been returned,
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then compares the results and decides which are "correct".
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The notion of "equality" of results,
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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",
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finds the minimum reported credit for the correct
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results of a given workunit,
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and assigns this amount of credit to all the correct results.
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This ensures that as long as a reasonable majority of participants
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don't falsify 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:
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validated and unvalidated.
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Users can see the workunits that didn't pass validation,
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or that were given reduced credit.
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