mirror of https://github.com/BOINC/boinc.git
70 lines
2.1 KiB
PHP
70 lines
2.1 KiB
PHP
<?
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require_once("docutil.php");
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page_head("Computation credit");
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echo "
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<p>
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Each project gives you <b>credit</b> for the computations your
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computers performs for the project.
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These credits are used to generate web-site 'leaderboards' showing
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individuals, teams, and categories (countries, CPU types, etc.)
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ranked by credit.
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<p>
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BOINC's credit system is based on a 'reference computer' that does
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<ul>
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<li>1 billion floating-point multiplies per second
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<li>1 billion integer multiplies per second
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<li>4 billion bytes per second of traffic to and from main memory
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(sequential, half reads and half writes)
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</ul>
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BOINC's unit of credit, the <b>Cobblestone</b> <sup>1</sup>,
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is one day of CPU time on the reference computer.
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<p>
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Each project maintains two types of credit:
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<ul>
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<li> <b>Total credit</b>:
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The total number of Cobblestones performed.
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<li> <b>Recent average credit</b>:
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The average number of Cobblestones per day performed recently.
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This average decreases by a factor of two every week.
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</ul>
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<p>
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Both types of credit (total and recent average)
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are maintained for each user and host.
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<h3>Leader boards</h3>
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The PHP pages supplied by BOINC include basic leaderboards:
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top users and hosts, by total and average.
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BOINC lets projects export the credit-related
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parts of their database as XML files.
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These XML files can be used to generate
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other breakdowns of users, hosts and teams,
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or to generate leaderboards based on the sum of
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credit from different projects.
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<h3>Possible future improvements</h3>
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<ul>
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<li>
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Ideally, credit should reflect network transfer and disk storage as well
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as computation.
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But it's hard to verify these activities,
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so for now they aren't included.
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<li>
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Eventually projects will develop applications that use
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graphics coprocessors or other non-CPU hardware.
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Credit should reflect the usage of such hardware.
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To accomplish this, we will need to let
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projects supply their own benchmarking functions.
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This will also handle the situation where a project's
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application does e.g. all integer arithmetic.
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</ul>
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<hr noshade size=1>
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<sup>1</sup> Named after Jeff Cobb of SETI@home
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";
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page_tail();
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?>
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