Inter-processor interrupt

In computing, an inter-processor interrupt (IPI), also known as a shoulder tap, is a special type of interrupt by which one processor may interrupt another processor in a multiprocessor system if the interrupting processor requires action from the other processor. Actions that might be requested include:

• Flush memory management unit caches, such as translation lookaside buffers, on other processors when memory mappings are changed by one processor;
• Stop when the system is being shut down by one processor.
• Notify an alternate CPU of a malfunction for Alternate CPU Recovery (ACR).
• Notify a processor that higher-priority work is available.
• Notify a processor of work that cannot be done on all processors due to, e.g.,
  • asymmetric access to I/O channels
  • special features on some processors