Method and Apparatus for Synthesizing Hardware Counters from Performance Sampling

• US 20080177756A1
• Filed: 01/18/2007
• Published: 07/24/2008
• Est. Priority Date: 01/18/2007
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Oracle America, Inc. (Oracle Corporation)
• Inventors: Tracton, Kenneth, Kosche, Nicolai
• Granted Patent: US 8,136,124 B2
• Time in Patent Office: Days
• US Class Current: 707/100
• CPC Class Codes: G06F 11/3447 Performance evaluation by modeling
• CPC Class Codes: G06F 11/3476 Data logging G06F11/14, G06F11/2205 take precedence
• CPC Class Codes: G06F 2201/86 Event-based monitoring
• CPC Class Codes: G06F 2201/88 Monitoring involving counting

Abstract

A system and method for performance monitoring may use data collected from a hardware event agent comprising a hardware sampling mechanism and/or one or more hardware counters to increment one or more synthesized performance counters by an amount dependent on an expression involving the collected data. Each synthesized performance counter may be configured to count events of a different type and may comprise a machine addressable storage location. The event types may include various memory references or misses, branches, branch mispredictions, or any other event of interest in performance monitoring. The hardware event agent may comprise one or more instruction counters, cycle counters, timers, or other hardware performance counters. One hardware performance counter may be used in a time-multiplexed or data-multiplexed manner to monitor events of multiple event types. The hardware sampling mechanism may return a statistical packet for sampled instructions, which may be examined to determine the event type.

Claims

1. A computer-implemented method, comprising:

a hardware counter counting to a predetermined value;

in response to the hardware counter reaching the predetermined value, collecting data corresponding to a runtime event;

determining if the runtime event is of a given event type; and

in response to determining that the runtime event is of the given event type, incrementing a synthesized counter configured to monitor events of the given event type, wherein the synthesized counter is implemented as a storage location in machine addressable memory.

2. The method of claim 1,

wherein said collecting data comprises:

sampling an instruction in response to the hardware counter reaching the predetermined value; and

receiving a packet comprising extended address information corresponding to the sampled instruction; and

wherein said determining is dependent on the extended address information comprised in the packet.

3. The method of claim 2, wherein the extended address information corresponding to the sampled information comprises one or more of:

a time, an identifier of a hardware component, an identifier of a software construct, an identifier of a data allocation, an identifier of a protocol, a register value, and a cost value.

4. The method of claim 2, further comprising:

determining if the runtime event is of an other event type dependent on the extended address information comprised in the packet; and

in response to determining that the sampled event is of the other event type, incrementing a different synthesized counter configured to monitor events of the other event type, wherein the different synthesized counter is implemented as a different storage location in machine addressable memory.

5. The method of claim 1, wherein said hardware counter comprises one of:

a hardware event counter, a hardware instruction counter, a hardware cycle counter, and a hardware timer.

6. The method of claim 1, wherein said collecting comprises capturing a value of a second hardware counter.

7. The method of claim 6, wherein said second hardware counter is configured to count events of the given type.

8. The method of claim 6, wherein said hardware counter is configured to count events of the given event type and said second hardware counter comprises one of:

a hardware event counter, a hardware instruction counter, a hardware cycle counter, and a hardware timer.

9. The method of claim 1, further comprising,

the hardware counter counting to a second predetermined value;

in response to the hardware counter reaching the second predetermined value, collecting data corresponding to a runtime event;

determining if the runtime event is of a second given event type; and

in response to determining that the runtime event is of the second given event type, incrementing a synthesized counter configured to monitor events of the second given event type, wherein the synthesized counter is implemented as a second storage location in machine addressable memory.

10. The method of claim 1, wherein the given event type comprises one of:

a data reference, a cache miss, a cache reference, a data translation buffer miss, a data translation buffer reference, a branch misprediction, and a hardware event counter condition.

11. The method of claim 1, wherein said incrementing the synthesized counter comprises incrementing the synthesized counter by an amount dependent on one or more of:

the predetermined value of the hardware counter, an instruction sampling rate, a value of an extended address element corresponding to a sampled instruction, a value of another hardware counter, a value of another synthesized counter, and a number of synthesized counters.

12. A computer system, comprising:

a processor comprising a hardware event agent; and

a memory comprising program instructions executable by the processor;

wherein the program instructions are configured to implement;

a plurality of software counters, each configured to monitor events of a different event type; and

a software event agent;

wherein the hardware event agent comprises a hardware counter; and

wherein the hardware event agent is configured to;

collect data corresponding to a runtime event in response to an overflow or underflow of the hardware counter;

wherein the software event agent is configured to;

determine an event type of the runtime event dependent on the collected data;

determine if one of the plurality of software counters is configured to monitor events of the determined event type; and

in response to determining that one of the plurality of software counters is configured to monitor events of the determined event type, increment the one of the plurality of software counters.

13. The computer system of claim 12, wherein the hardware event agent further comprises an instruction sampling mechanism;

wherein to collect said data corresponding to the runtime event, the instruction sampling mechanism is configured to sample an instruction in response to the overflow or underflow of the hardware counter.

14. The computer system of claim 12, wherein to increment the one of the plurality of software counters, the software event agent is configured to increment the one of the plurality of software counters by an amount dependent on one or more of:

a value of the hardware counter, an instruction sampling rate, a value of an extended address element corresponding to a sampled instruction, a value of another hardware counter, a value of another synthesized counter, and a number of synthesized counters.

15. The computer system of claim 12, wherein the hardware event agent further comprises a second hardware counter;

wherein to collect said data corresponding to the runtime event, the hardware event agent is configured to capture a value of the second hardware counter in response to the overflow or underflow of the hardware counter.

16. The computer system of claim 12, wherein the hardware event agent is further configured to:

collect data corresponding to a second runtime event in response to a second overflow or underflow of the hardware counter;

wherein the software event agent is further configured to;

determine an event type of the second runtime event dependent on the collected data corresponding to the second runtime event;

determine if one of the plurality of software counters is configured to monitor events of the determined event type of the second runtime event; and

in response to determining that one of the plurality of software counters is configured to monitor events of the determined event type of the second runtime event, increment the one of the plurality of software counters.

17. A computer-readable storage medium comprising program instructions computer-executable to implement a plurality of software counters each configured to count events of a different event type, and a software event agent;

wherein the software event agent is configured to;

receive information about a runtime event from a hardware event agent in response to the hardware event agent detecting an overflow or an underflow of a hardware event counter, a hardware instruction counter, a hardware cycle counter, or a hardware timer;

determine an event type of the runtime event dependent on the received information;

determine if one of the plurality of software counters is configured to monitor events of the determined event type; and

in response to determining that one of the plurality of software counters is configured to monitor events of the determined event type, increment the one of the plurality of software counters.

18. The storage medium of claim 17, wherein to increment the one of the plurality of software counters, the software event agent is configured to increment the one of the plurality of software counters by an amount dependent on one or more of:

a value of a hardware event counter, a hardware instruction counter, a hardware cycle counter, or a hardware timer comprised in the hardware event agent;

an instruction sampling rate;

a value of an extended address element corresponding to a sampled instruction;

a value of another synthesized counter; and

a number of synthesized counters.

19. The storage medium of claim 17, wherein the information about the runtime event received from the hardware event agent comprises extended address information corresponding to a sampled instruction;

and wherein said determining an event type is dependent on the extended address information.

20. The storage medium of claim 17, wherein the information about the runtime event received from the hardware event agent comprises a value of a second hardware counter, said second hardware counter configured to count events of the determined event type.