Restartable Processes and Persistent Memory

As previously discussed in "Memory Requirements and Design Constraints", the system uses persistent memory to store the following data for each executing restartable process:

• The process's process image: a copy of the text and initialized data segments from which the process will be loaded after a restart.

• The process's executing image: a copy of the text and data from which the process is executed.

This data is stored in three persistent memory blocks. One memory block is used for the process image, one is used for the executed text, and the last is used for the process data. These blocks are allocated and freed upon requests from the Hot Restart Controller to the Persistent Memory Manager. Other processes cannot access or free these persistent memory blocks. However, restartable processes can allocate additional blocks under the control of the Hot Restart Controller. This is described in "Freeing Persistent Memory".