Support for Perf Maps¶
On supported platforms (as of this writing, only Linux), the runtime can take
advantage of perf map files to make Python functions visible to an external
profiling tool (such as perf).
A running process may create a file in the
/tmp directory, which contains entries
that can map a section of executable code to a name. This interface is described in the
documentation of the Linux Perf tool.
In Python, these helper APIs can be used by libraries and features that rely on generating machine code on the fly.
Note that holding the Global Interpreter Lock (GIL) is not required for these APIs.
/tmp/perf-$pid.mapfile, unless it’s already opened, and create a lock to ensure thread-safe writes to the file (provided the writes are done through
PyUnstable_WritePerfMapEntry()). Normally, there’s no need to call this explicitly; just use
PyUnstable_WritePerfMapEntry()and it will initialize the state on first call.
-1on failure to create/open the perf map file, or
-2on failure to create a lock. Check
errnofor more information about the cause of a failure.
int PyUnstable_WritePerfMapEntry(const void *code_addr, unsigned int code_size, const char *entry_name)¶
Write one single entry to the
/tmp/perf-$pid.mapfile. This function is thread safe. Here is what an example entry looks like:
# address size name 7f3529fcf759 b py::bar:/run/t.py
PyUnstable_PerfMapState_Init()before writing the entry, if the perf map file is not already opened. Returns
0on success, or the same error codes as