Managing high speed memory

A method of managing a high speed memory, the method comprising:

• determining, in response to receipt of a demotion request, margin performance losses corresponding to respective non-free indexes, wherein corresponding non-free indexes are set for different types of low speed memory, wherein each non-free index comprises index entries indicating a storage unit in a high speed memory assigned to a corresponding low speed memory, wherein a storage unit in the high speed memory is recovered by demoting an index entry from a given non-free index, wherein a given margin performance loss represents a change in a processor read operation time caused by performing a demotion operation in a corresponding non-free index;
• comparing the margin performance losses of the respective non-free indexes and selecting as a demotion index a non-free index whose margin performance loss satisfies a demotion condition;
• and
• selecting an index entry from the demotion index to perform the demotion operation,
• wherein determining margin performance losses comprises:
• determining a margin hit rate loss corresponding to the respective non-free index;
• determining a synthesized response time corresponding to the respective non-free index, wherein the synthesized response time corresponding to the respective non-free index is a weighted average of predicted values of the average response time of the low speed memories corresponding to the respective non-free index according to predicted numbers of accesses;
• and
• multiplying the margin hit rate loss by the synthesized response time determine the margin performance loss.