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Bug 1814105: part 6 - Update jit profiling documentation. r=iain

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Depends on D168587

Differential Revision: https://phabricator.services.mozilla.com/D168588
This commit is contained in:
Denis Palmeiro 2023-02-16 14:07:57 +00:00
parent a62b33bd5b
commit d048d2ff45
1 changed files with 8 additions and 9 deletions
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17
docs/performance/jit_profiling_with_perf.md
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@ -15,16 +15,15 @@ ac_add_options --enable-perf
## Environment Variables
Two environment variables are available for perf JIT profiling:
Environment variables that must be defined for perf JIT profiling:
The first environment variable must be defined for SpiderMonkey to generate the necessary jitdump binary files for JIT profiling.
The supported values are "ir", "src" and "func". `IONPERF=ir` will enable IR annotation, `IONPERF=src` will enable source code annotation **only if** perf can read the source file locally. `IONPERF=func` will disable all annotation and only function names will be available. It is recommended to use `IONPERF=ir` for most situations.
`PERF_SPEW_OUTPUT`: Location of jitdump output files. Making this directory a tmpfs filesystem could help reduce overhead.\
`IONPERF`: Valid options include: `func`, `src`, `ir`, `ir-ops`.
The second environment variable is optional, but is highly recommended to avoid polluting your cwd by putting all jitdump files into a separate directory:
```
mkdir output
export PERF_SPEW_DIR=output
```
`IONPERF=func` will disable all annotation and only function names will be available. It is the fastest option.\
`IONPERF=ir` will enable IR annotation.\
`IONPERF=ir-ops` will enable IR annotation with operand support. **Requires --enable-jitspew** and adds additional overhead to "ir".\
`IONPERF=src` will enable source code annotation **only if** perf can read the source file locally. Only really works well in the JS shell.
## Profiling the JS shell
@ -52,7 +51,7 @@ perf inject -j -i perf.data -o jit.data
View the profile:
```
perf report --no-children -i jit.data
perf report --no-children --call-graph=graph,0 -i jit.data
```
All of the above commands can be put into a single shell script.