Stowage/cpython
2
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2026-06-05 01:10:53 +00:00
Code Issues Projects Releases Packages Wiki Activity

gh-149584: Fix excessive overhead in the Tachyon profiler regarding the cache behavior (#149649)

Browse source 
Use exact remote reads for interpreter state, thread state, and
interpreter frame structs instead of pulling full remote pages into the
profiler page cache. This matches the core change from
python/cpython#149585.

The profiler clears the page cache between samples, so live entries are
always packed at the front. Track the live count and only clear/search
that prefix instead of scanning all 1024 slots on the hot path.

Use the frame cache to predict the next thread state and top frame
address, then batch interpreter/thread/frame reads with process_vm_readv
when profiling a Linux target. Reuse prefetched frame buffers in the
frame walker when the prediction is valid.

Cache the last FrameInfo tuple per code object/instruction offset, reuse
cached thread id objects, and append cached parent frames directly on
full frame-cache hits. This cuts Python allocation churn in the
steady-state profiler path.
This commit is contained in:
Pablo Galindo Salgado 2026-05-20 04:32:08 -07:00 • committed by GitHub
parent 06a2830aa8
commit 661df25692
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
12 changed files with 739 additions and 127 deletions
Download patch file Download diff file Expand all files Collapse all files

13
Modules/_remote_debugging/code_objects.c
View file

@ -405,6 +405,8 @@ parse_code_object(RemoteUnwinderObject *unwinder,
meta->func_name = func;
meta->file_name = file;
meta->linetable = linetable;
meta->last_frame_info = NULL;
meta->last_addrq = -1;
meta->first_lineno = GET_MEMBER(int, code_object, unwinder->debug_offsets.code_object.firstlineno);
meta->addr_code_adaptive = real_address + (uintptr_t)unwinder->debug_offsets.code_object.co_code_adaptive;
@ -482,6 +484,12 @@ parse_code_object(RemoteUnwinderObject *unwinder,
addrq = (uint16_t *)ip - (uint16_t *)meta->addr_code_adaptive;
#endif
; // Empty statement to avoid C23 extension warning
if (!unwinder->opcodes && meta->last_frame_info != NULL && meta->last_addrq == addrq) {
*result = Py_NewRef(meta->last_frame_info);
return 0;
}
LocationInfo info = {0};
bool ok = parse_linetable(addrq, PyBytes_AS_STRING(meta->linetable),
PyBytes_GET_SIZE(meta->linetable),
@ -529,6 +537,11 @@ parse_code_object(RemoteUnwinderObject *unwinder,
goto error;
}
if (!unwinder->opcodes) {
Py_XSETREF(meta->last_frame_info, Py_NewRef(tuple));
meta->last_addrq = addrq;
}
*result = tuple;
return 0;