Dynamic trap table interposition for efficient collection of trap statistics

A method of monitoring the performance of a computer system comprising:

• a) changing a base address of a trap table from a first address to a second address;
• b) executing instructions of an instrumented trap table to generate first performance statistics;
• c) responsive to said b), transferring control to instructions of a non-instrumented trap table;
• and
• d) responsive to said c), transferring control to instructions of said instrumented trap table to generate second performance statistics.

A method of determining the overhead of performance monitoring comprising:

• a) measuring a first time to execute a first number of traps without performance monitoring;
• b) computing a first average time by dividing said time by said first number;
• and
• c) measuring a second time to execute a second number of traps with performance monitoring;
• d) computing a second average time by dividing said time by said second number;
• and
• e) calculating the overhead as the difference between said first average time and said second average time.

A method for monitoring the performance of a computer system comprising:

• a) changing a base address of a trap table from a first address to a second address for invoking trap statistics collection;
• b) executing an instrumented trap table to generate said trap statistics;
• and
• c) displaying said trap statistics in visual form.

A system comprising:

• a processor coupled to a bus;
• and
• a memory coupled to said bus and wherein said memory contains instructions that when executed implement a method for monitoring the performance of a computer system, said method comprising:
• a) changing a base address of a trap table from a first address to a second address;
• and
• b) executing an instrumented trap table to generate performance statistics.