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GH-100240: Generic freelist, applied to ints #101453

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iritkatriel wants to merge 19 commits into from
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GH-100240: Generic freelist, applied to ints #101453

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e953c57
freelist for ints
iritkatriel Jan 30, 2023
cf99ee4
moved things around a little
iritkatriel Jan 31, 2023
8a6e6a3
remove WITH_FREELISTS in longobject.c
iritkatriel Jan 31, 2023
fe65f49
FreeToFull leaves the list empty
iritkatriel Jan 31, 2023
a33061f
reuse _PyFreeList_Clear
iritkatriel Feb 3, 2023
6b312e0
fix free bug and remove ifdef in a few places
iritkatriel Feb 3, 2023
1d81198
use _PyLong_Free in specialized bytecodes
iritkatriel Feb 3, 2023
5609e30
use _PyLong_Free in _Py_DECREF_INT
iritkatriel Feb 3, 2023
b8b1879
stats for generic freelist
iritkatriel Feb 5, 2023
460d12c
print new stats
iritkatriel Feb 6, 2023
2e2a861
fix index mapping
iritkatriel Feb 6, 2023
42ee27f
tweak the stats
iritkatriel Feb 7, 2023
a9e76ad
shift instead of div
iritkatriel Feb 8, 2023
1134727
Merge remote-tracking branch 'upstream/main' into int-freelist
iritkatriel Feb 8, 2023
78592b9
int --> Py_ssize_t
iritkatriel Feb 8, 2023
044743e
disable the freelist after clearing it in interpreter_clear
iritkatriel Feb 8, 2023
827b81b
add _PyFreeList_Disable
iritkatriel Feb 9, 2023
51c6c3c
rename INDEX --> SIZE_CLASS
iritkatriel Feb 10, 2023
cfb886d
stats per size class
iritkatriel Feb 10, 2023
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moved things around a little
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@iritkatriel
iritkatriel committed Jan 31, 2023
commit cf99ee400307037bf7b6fa9267235c36a5c09927
27 changes: 16 additions & 11 deletions Include/internal/pycore_interp.h
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Expand Up @@ -50,7 +50,6 @@ struct _Py_long_state {


/* interpreter state */
#define WITH_FREELISTS 1

#define SMALL_OBJECT_FREELIST_SIZE 1024
#define INTERP_NUM_FREELISTS 30
Expand Down Expand Up @@ -238,26 +237,32 @@ PyAPI_FUNC(int) _PyInterpreterState_IDInitref(PyInterpreterState *);
PyAPI_FUNC(int) _PyInterpreterState_IDIncref(PyInterpreterState *);
PyAPI_FUNC(void) _PyInterpreterState_IDDecref(PyInterpreterState *);

#define SIZE_TO_FREELIST_INDEX(size) ((size-4)/2)
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@markshannon markshannon Feb 3, 2023 •
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Why divide by 2 and not 2 * sizeof(void *), which is the quantum of allocation for malloc and ob_malloc?
(Assuming that the size is in bytes)
Could you use the term "size class" or equivalent, instead of "freelist index" The mapping here is from sizes to classes (not all size classes get free lists).

Any reason not to make this an inline function?

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@markshannon markshannon Feb 3, 2023

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Alternatively, put an assert in this function, and put a size check in the caller.

#define FREELIST_INDEX_TO_SIZE(idx) (2*(idx) + 4)

#if WITH_FREELISTS
static inline PyObject*
_PyInterpreterState_FreelistAlloc(PyInterpreterState *interp, int size) {
assert(size >= 4);
assert((size & 0x1) == 0);
int index = (size-4)/2;
_PyInterpreterState_FreelistAlloc(PyInterpreterState *interp, Py_ssize_t size) {
#if WITH_FREELISTS
int index = SIZE_TO_FREELIST_INDEX(size);
assert(index >= 0 && index < INTERP_NUM_FREELISTS);
return _PyFreeList_Alloc(&interp->freelists[index]);
#else
return PyObject_Malloc(size);
#endif
}

static inline void
_PyInterpreterState_FreelistFree(PyInterpreterState * interp, PyObject *op, int size) {
_PyInterpreterState_FreelistFree(PyInterpreterState * interp, PyObject *op, Py_ssize_t size) {
#if WITH_FREELISTS
/* todo: assert the size is correct? */
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assert(size >= 4);
assert((size & 0x1) == 0);
int index = (size-4)/2;
int index = SIZE_TO_FREELIST_INDEX(size);
assert(index >= 0 && index < INTERP_NUM_FREELISTS);
_PyFreeList_Alloc(&interp->freelists[index]);
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#else
Py_TYPE(op)->tp_free((PyObject *)op);
#endif
}

#endif /* WITH_FREELISTS */


#ifdef __cplusplus
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1 change: 0 additions & 1 deletion Include/internal/pycore_pymem.h
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Expand Up @@ -90,7 +90,6 @@ PyAPI_FUNC(int) _PyMem_GetAllocatorName(
PYMEM_ALLOCATOR_NOT_SET does nothing. */
PyAPI_FUNC(int) _PyMem_SetupAllocators(PyMemAllocatorName allocator);

#define WITH_FREELISTS 1

#if WITH_FREELISTS
/* Free lists.
Expand Down
2 changes: 1 addition & 1 deletion Objects/obmalloc.c
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Expand Up @@ -738,9 +738,9 @@ _PyFreeList_HalfFillAndAllocate(_PyFreeList *list)
if (i == 0) {
return NULL;
}
list->space -= (i-1);
void *result = list->ptr;
list->ptr = *((void **)result);
list->space -= (i-1);
return result;
}

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4 changes: 3 additions & 1 deletion Python/pystate.c
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Expand Up @@ -654,7 +654,9 @@ PyInterpreterState_New(void)

#if WITH_FREELISTS
for (int i=0; i < INTERP_NUM_FREELISTS; i++) {
_PyFreeList_Init(&interp->freelists[i], 4 + 2*i, SMALL_OBJECT_FREELIST_SIZE);
_PyFreeList_Init(&interp->freelists[i],
FREELIST_INDEX_TO_SIZE(i),
SMALL_OBJECT_FREELIST_SIZE);
}
#endif
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