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JIT symbols
Table of contents
Java JIT symbols
On Android >= P, simpleperf supports profiling Java code, no matter whether it is executed by the interpreter, or JITed, or compiled into native instructions. So you don't need to do anything.
For details on Android O and N, see android_application_profiling.md.
Generic JIT symbols
Simpleperf supports picking up symbols from per-pid symbol map files, somewhat similar to what Linux kernel perftool does. Application should create those files at specific locations.
Symbol map file location for application
Application should create symbol map files in its data directory.
For example, process 123 of application foo.bar.baz should create
/data/data/foo.bar.baz/perf-123.map.
Symbol map file location for standalone program
Standalone programs should create symbol map files in /data/local/tmp.
For example, standalone program process 123 should create /data/local/tmp/perf-123.map.
Symbol map file format
Symbol map file is a text file.
Every line describes a new symbol. Line format is:
<symbol-absolute-address> <symbol-size> <symbol-name>
For example:
0x10000000 0x16 jit_symbol_one
0x20000000 0x332 jit_symbol_two
0x20002004 0x8 jit_symbol_three
Known issues
Current implementation gets confused if memory pages where JIT symbols reside are reused by mapping a file either before or after.
For example, if memory pages were first used by dlopen("libfoo.so"), then freed by dlclose,
then allocated for JIT symbols - simpleperf will report symbols from libfoo.so instead.