Minimizing bandwith to compress output stream in instruction tracing systems

A system comprising:

• a memory;
• and
• a processing device communicably coupled to the memory, wherein the processing device comprising:
• a scheduler and execution unit;
• and
• a retirement unit communicably coupled to the scheduler and execution unit, the retirement unit comprising an instruction tracing (IT) module to:
• identify a current instruction in a trace of the IT module as a conditional branch (CB) instruction;
• execute one of generate a first CB packet comprising a byte pattern with an indication of outcome of the CB instruction, or add an indication of the outcome of the CB instruction to the byte pattern of an existing CB packet;
• generate an IT packet in response to determining that a subsequent instruction in the trace after the current instruction is not the CB instruction, wherein the IT packet is different from the first CB packet or the existing CB packet;
• add the IT packet into a deferred queue in response to determining that the packet is deferrable, wherein the deferred queue comprises a deferred packet;
• output the first CB packet or the existing CB packet followed by the deferred packet, followed by the IT packet into a packet log in response to determining that the IT packet is not deferrable, wherein determining that the IT packet is not deferrable is based on at least one of a first or a second condition is met, wherein the first condition comprises a total number of bits in the byte pattern of the first CB packet or the existing CB packet reach a first threshold, wherein the second condition comprises a total number of packets in the deferred queue reach a second threshold.

A method of a processing device comprising:

• identifying a current instruction in a trace of the IT module as a conditional branch (CB) instruction;
• executing one of generate a first CB packet comprising a byte pattern with an indication of outcome of the CB instruction, or add an indication of the outcome of the CB instruction to the byte pattern of an existing CB packet;
• generating a an IT packet in response to determining that a subsequent instruction in the trace after the current instruction is not the CB instruction, wherein the IT packet is different from the first CB packet or the existing CB packet;
• adding the IT packet into a deferred queue in response to determining that the packet is deferrable, wherein the deferred queue comprises a deferred packet;
• outputting the first CB packet or the existing CB packet followed by the deferred packet, followed by the IT packet into a packet log in response to determining that the IT packet is not deferrable, wherein determining that the IT packet is not deferrable is based on at least one of a first or a second condition is met, wherein the first condition comprises a total number of bits in the byte pattern of the first CB packet or the existing CB packet reach a first threshold, wherein the second condition comprises a total number of packets in the deferred queue reach a second threshold.

A non-transitory machine-readable storage medium including data that, when accessed by a processing device, cause the processing device to perform operations comprising:

• identifying a current instruction in a trace of the IT module as a conditional branch (CB) instruction;
• executing one of generate a first CB packet comprising a byte pattern with an indication of outcome of the CB instruction, or add an indication of the outcome of the CB instruction to the byte pattern of an existing CB packet;
• generating an IT packet in response to determining that a subsequent instruction in the trace after the current instruction is not the CB instruction, wherein the IT packet is different from the first CB packet or the existing CB packet;
• adding the IT packet into a deferred queue in response to determining that the packet is deferrable, wherein the deferred queue comprises a deferred packet;
• outputting the first CB packet or the existing CB packet followed by the deferred packet, followed by the IT packet into a packet log in response to determining that the IT packet is not deferrable, wherein determining that the IT packet is not deferrable is based on at least one of a first or a second condition is met, wherein the first condition comprises a total number of bits in the byte pattern of the first CB packet or the existing CB packet reach a first threshold, wherein the second condition comprises a total number of packets in the deferred queue reach a second threshold.