HCoop / hcoop / debian / mlton.git / blame
| Commit | Line | Data |
|---|---|---|
| 7f918cf1 CE |
1 | ProfilingCounts |
| 2 | =============== | |
| 3 | ||
| 4 | With MLton and `mlprof`, you can <:Profiling:profile> your program to | |
| 5 | find out how many times each function is called and how many times | |
| 6 | each branch is taken. To do so, compile your program with | |
| 7 | `-profile count -profile-branch true`. For example, suppose that | |
| 8 | `tak.sml` contains the following. | |
| 9 | ||
| 10 | [source,sml] | |
| 11 | ---- | |
| 12 | sys::[./bin/InclGitFile.py mlton master doc/examples/profiling/tak.sml] | |
| 13 | ---- | |
| 14 | ||
| 15 | Compile with count profiling and run the program. | |
| 16 | ---- | |
| 17 | % mlton -profile count -profile-branch true tak.sml | |
| 18 | % ./tak | |
| 19 | ---- | |
| 20 | ||
| 21 | Display the profiling data, along with raw counts and file positions. | |
| 22 | ---- | |
| 23 | % mlprof -raw true -show-line true tak mlmon.out | |
| 24 | 623,610,002 ticks | |
| 25 | function cur raw | |
| 26 | --------------------------------- ----- ------------- | |
| 27 | Tak.tak1.tak2 tak.sml: 5 38.2% (238,530,000) | |
| 28 | Tak.tak1.tak2.<true> tak.sml: 7 27.5% (171,510,000) | |
| 29 | Tak.tak1 tak.sml: 3 10.7% (67,025,000) | |
| 30 | Tak.tak1.<true> tak.sml: 14 10.7% (67,025,000) | |
| 31 | Tak.tak1.tak2.<false> tak.sml: 9 10.7% (67,020,000) | |
| 32 | Tak.tak1.<false> tak.sml: 16 2.0% (12,490,000) | |
| 33 | f tak.sml: 23 0.0% (5,001) | |
| 34 | f.<branch> tak.sml: 25 0.0% (5,000) | |
| 35 | f.<branch> tak.sml: 23 0.0% (1) | |
| 36 | uncalled tak.sml: 29 0.0% (0) | |
| 37 | f.<branch> tak.sml: 24 0.0% (0) | |
| 38 | ---- | |
| 39 | ||
| 40 | Branches are displayed with lexical nesting followed by `<branch>` | |
| 41 | where the function name would normally be, or `<true>` or `<false>` | |
| 42 | for if-expressions. It is best to run `mlprof` with `-show-line true` | |
| 43 | to help identify the branch. | |
| 44 | ||
| 45 | One use of `-profile count` is as a code-coverage tool, to help find | |
| 46 | code in your program that hasn't been tested. For this reason, | |
| 47 | `mlprof` displays functions and branches even if they have a count of | |
| 48 | zero. As the above output shows, the branch on line 24 was never | |
| 49 | taken and the function defined on line 29 was never called. To see | |
| 50 | zero counts, it is best to run `mlprof` with `-raw true`, since some | |
| 51 | code (e.g. the branch on line 23 above) will show up with `0.0%` but | |
| 52 | may still have been executed and hence have a nonzero raw count. |