slide 33 of 40

Gang Scheduling

• Coordinate local process schedulers to timeshare sets of related processes across a cluster
• Problems:
  • One easy solution, synchronizing scheduler clocks, turns out to be impossible
  • There are always localized "noise processes" (e.g., disk buffer flushes, paging traffic)
• Can be implemented using PAPERS aggregate interrupts to awaken a priv process that turns process priority up/down to encourage a schedule
• Similar things could be done for SMPs, but conventional networks make the interrupts too slow...