Sometimes the client may receive tasks having report deadline much earlier than tasks received earlier.

If the client is configured with a large work buffer, this could cause these tasks expire before they are worked on.

Can the client be configured to select the next task based on the deadline?

Sometimes it doesn't. I had this one too, BOINC computed wrong task.

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Can the client be configured to select the next task based on the deadline?

Yes and No! What Sekerob says is that you can't configure the client that way. But yes, it is already configured to do exactly that: when BOINC recognizes that a task is in danger of not finishing before deadline, it enters "Earliest Deadline First" (EDF) mode and handles that task with high priority. That has nothing to do with the machine process's priority (nice value), but means that no other BOINC task is allowed to run until either the job in danger of missing its deadline has finished or the condition is otherwise changed.

Gruß,
Gundolf

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Computer sind nicht alles im Leben. (Kleiner Scherz)