Computation credit

Each project gives you credit for the computations your computers performs for the project. These credits are used to generate web-site "leaderboards" showing individuals, teams, and categories (countries, CPU types, etc.) ranked by credit.

BOINC's credit system is based on a unit of computation called a Cobblestone, defined as

• 1 billion floating-point multiply/adds
• 1 billion integer multiply/adds
• 4 billion bytes of traffic to and from main memory (sequential, half reads and half writes)

In principle, credit should reflect network transfer and disk storage as well as computation. But it's hard to verify these activities, so for now they aren't included.

Each project maintains two types of credit:

• Total credit: The total number of Cobblestones performed.
• Recent average credit: The average number of Cobblestones per second performed recently ("recently" is defined by an exponential function that decays by a factor of e every week).

Both types of credit are maintained for both users and hosts.