Facilitating recording a trace file of code execution using way-locking in a set-associative processor cache

• US 10,324,851 B2
• Filed: 02/15/2017
• Issued: 06/18/2019
• Est. Priority Date: 10/20/2016
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Mola, Jordi
• Primary Examiner(s): Nguyen, Hiep T
• Application Number:
  US15/433,918
• Publication Number:
  US 20180113809A1
• Time in Patent Office: 853 Days
• Field of Search: 711122
• CPC Class Codes: G06F 11/3037 where the computing system component is a memory, e.g. virtual memory, cache accessing, addressing or allocating within memory systems or architectures G06F12/00; checking stores for correct operation G11C29/00
• CPC Class Codes: G06F 11/34 Recording or statistical evaluation of computer activity, e.g. of down time, of input/output operation ; Recording or statistical evaluation of user activity, e.g. usability assessment
• CPC Class Codes: G06F 11/3471 Address tracing
• CPC Class Codes: G06F 11/36 Preventing errors by testing or debugging software
• CPC Class Codes: G06F 11/3636 by tracing the execution of the program
• CPC Class Codes: G06F 12/0842 for multiprocessing or multitasking
• CPC Class Codes: G06F 12/0864 using pseudo-associative means, e.g. set-associative or hashing
• CPC Class Codes: G06F 12/126 with special data handling, e.g. priority of data or instructions, handling errors or pinning
• CPC Class Codes: G06F 2201/885 Monitoring specific for caches
• CPC Class Codes: G06F 2212/1008 Correctness of operation, e.g. memory ordering
• CPC Class Codes: G06F 2212/502 using adaptive policy

Abstract

Facilitating recording a trace of code execution using way-locking in a set-associative processor cache. A computing device reserves cache line(s) in set(s) of cache lines of a set-associative cache for caching only locations in the system memory that are allocated to a particular executable entity. During a traced execution of the particular executable entity, the computing device detects that a cache miss has occurred on a location in the system memory that is allocated to a particular executable entity, and that a value at the location of system memory is being cached into one of the reserved cache lines. Based on the value at the location of system memory being cached into a reserved cache line, the computing device logs into a trace data stream at least a portion of the value at the location of system memory being cached into the reserved cache line.

Claims

1. A computing device for facilitating recording a trace of code execution using a set-associative processor cache, the computing device comprising:

one or more processing units associated with at least one set-associative processor cache that includes a plurality of sets of cache lines, each set comprising two or more different cache lines;

system memory; and

one or more computer-readable media having stored thereon computer-executable instructions that are executable by the one or more processing units to cause the computing device to perform at least the following;

reserve one or more cache lines in one or more of the plurality of sets of cache lines for caching only locations in the system memory that are allocated to a particular executable entity;

during a traced execution of the particular executable entity, detect that a cache miss has occurred on a location in the system memory that is allocated to a particular executable entity, and that a value at the location of system memory has been, or is to be, cached into one of the reserved cache lines; and

based at least on the value at the location of system memory being cached into one of the reserved cache lines, log into a trace data stream at least a portion of the value at the location of system memory being cached into the one of the reserved cache lines.

2. The computing device of claim 1, wherein locations in the system memory that are allocated to a particular executable entity are identified based at least on a memory address corresponding to a page table for a memory space of the particular executable entity.

3. The computing device of claim 2, wherein at least a portion of the memory address is stored in a processor register.

4. The computing device of claim 3, wherein the at least a portion of the memory address stored in the processor register is used by the computing device to detect that the cache miss has occurred on the location in the system memory that is allocated to a particular executable entity.

5. The computing device of claim 1, wherein reserving one or more cache lines in one or more of the plurality of sets of cache lines comprises reserving one or more cache lines in each of the plurality of sets of cache lines.

6. The computing device of claim 1, wherein reserving one or more cache lines in one or more of the plurality of sets of cache lines comprises reserving the one or more cache lines based on way number.

7. The computing device of claim 1, wherein reserving one or more cache lines in one or more of the plurality of sets of cache lines comprises requesting a way-lock of the one or more processing units.

8. The computing device of claim 1, wherein logging into the trace data stream at least a portion of the value at the location of system memory being cached into the one of the reserved cache lines also comprises logging at least a portion of an address of the location in the system memory.

9. A method, implemented at a computing device that includes one or more processing units associated with at least one set-associative processor cache that includes a plurality of sets of cache lines, each set comprising two or more different cache lines, for facilitating recording a trace of code execution using a set-associative processor cache, the method comprising:

locking one or more cache lines in one or more of the plurality of sets of cache lines for caching only locations in a system memory that are allocated to a particular executable entity;

during a traced execution of the particular executable entity, detecting that a cache miss has occurred on a location in the system memory that is allocated to a particular executable entity, and that a value at the location of system memory has been, or is to be, cached into one of the locked cache lines; and

based at least on the value at the location of system memory being cached into one of the locked cache lines, logging into a trace data stream at least a portion of the value at the location of system memory being cached into the one of the locked cache lines.

10. The method of claim 9, wherein locations in the system memory that are allocated to a particular executable entity are identified based at least on a memory address corresponding to a page table for a memory space of the particular executable entity.

11. The method of claim 10, wherein one or more portions of the memory address are stored in a processor register.

12. The method of claim 11, wherein the one or more portions of the memory address are stored in the processor register are used by the computing device to detect that the cache miss has occurred on the location in the system memory that is allocated to a particular executable entity.

13. The method of claim 9, wherein locking one or more cache lines in one or more of the plurality of sets of cache lines comprises locking one or more cache lines in each of the plurality of sets of cache lines.

14. The method of claim 9, wherein locking one or more cache lines in one or more of the plurality of sets of cache lines comprises locking the one or more cache lines based on way number.

15. The method of claim 9, wherein locking one or more cache lines in one or more of the plurality of sets of cache lines comprises requesting a way-lock of the one or more processing units.

16. The method of claim 9, wherein logging into the trace data stream at least a portion of the value at the location of system memory being cached into the one of the locked cache lines also comprises logging at least a portion of an address of the location in the system memory.

17. A computing device, comprising:

one or more processing units;

a processor cache that includes a plurality of cache lines; and

stored control logic that is configured to;

group the plurality cache lines into a plurality of sets of cache lines, each set comprising two or more different cache lines;

based upon a request, lock one or more cache lines in one or more of the plurality of sets of cache lines for caching only locations in system memory that are identified based upon a memory address associated with a traced executable entity;

detect a cache miss on a particular location in the system memory that is identified based upon the memory address associated with the traced executable entity; and

as a result of detecting the cache miss,

cache a value at the particular location in the system memory; and

initiate logging of the value at the particular location in the system memory into a log file associated with tracing of the traced executable entity.

18. The computing device of claim 17, wherein detecting the cache miss on the particular location in the system memory that is identified based upon the memory address associated with the traced executable entity comprises comparing an address of the particular location in the system memory to a register containing at least a portion of the memory address associated with the traced executable entity.

19. The computing device of claim 17, wherein initiating logging of the value at the particular location in the system memory into the log file associated with tracing of the traced executable entity comprises sending a message to a debugging application.

20. The computing device of claim 17, wherein locking the one or more cache lines comprise performing a way-locking operation.