Elapsed Cycle Timer in Last Branch Records

A method, comprising:

• recording, by a processing device in an entry of a last branch record (LBR) structure of the processing device, an address instruction pointer (IP) of a branch instruction executed by the processing device, wherein the LBR structure is implemented in at least one register of the processing device;
• recording, in the entry of the LBR structure, an address IP of a target of the branch instruction;
• sampling a value of a LBR counter;
• recording the value of the LBR counter in an elapsed time field of the entry of the LBR structure;
• and
• resetting the LBR counter.

An system comprising:

• a memory to store a branch instruction;
• and
• a processing device communicably coupled to the memory, the processing device comprising:
• an execution unit to execute the branch instruction;
• a last branch record (LBR) counter to iterate with each cycle of the execution unit;
• and
• at least one register communicably coupled to the LBR counter, the at least one register to, responsive to execution of the branch instruction by the execution unit:
• store, in an LBR entry of an LBR structure provided by the at least one register, an address instruction pointer (IP) of the branch instruction;
• store, in the LBR entry, an address IP of a target of the branch instruction;
• and
• store, in an elapsed time filed of the LBR entry, a value sampled from the LBR counter upon creation of the LBR entry.