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Improve GC finalisation code; add option to disable it.

This commit is contained in:
Damien George 2014-04-05 20:35:48 +01:00
parent 8123a3339d
commit 12bab72d93
12 changed files with 135 additions and 58 deletions
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150
py/gc.c
View File

@ -27,15 +27,17 @@ typedef unsigned char byte;
#define STACK_SIZE (64) // tunable; minimum is 1
STATIC byte *gc_alloc_table_start;
STATIC byte *gc_mpobj_table_start;
STATIC machine_uint_t gc_alloc_table_byte_len;
STATIC machine_uint_t gc_mpobj_table_byte_len;
#if MICROPY_ENABLE_FINALISER
STATIC byte *gc_finaliser_table_start;
#endif
STATIC machine_uint_t *gc_pool_start;
STATIC machine_uint_t *gc_pool_end;
STATIC int gc_stack_overflow;
STATIC machine_uint_t gc_stack[STACK_SIZE];
STATIC machine_uint_t *gc_sp;
STATIC bool gc_lock;
// ATB = allocation table byte
// 0b00 = FREE -- free block
@ -67,38 +69,58 @@ STATIC machine_uint_t *gc_sp;
#define ATB_HEAD_TO_MARK(block) do { gc_alloc_table_start[(block) / BLOCKS_PER_ATB] |= (AT_MARK << BLOCK_SHIFT(block)); } while (0)
#define ATB_MARK_TO_HEAD(block) do { gc_alloc_table_start[(block) / BLOCKS_PER_ATB] &= (~(AT_TAIL << BLOCK_SHIFT(block))); } while (0)
#define ATB_SET_MPOBJ(block) do { gc_mpobj_table_start[(block) / 8] |= (1<<(block%8)); } while (0)
#define ATB_CLR_MPOBJ(block) do { gc_mpobj_table_start[(block) / 8] &= (~(1<<(block%8))); } while (0)
#define ATB_IS_MPOBJ(block) ((gc_mpobj_table_start[(block) / 8]>>(block%8))&0x01)
#define BLOCK_FROM_PTR(ptr) (((ptr) - (machine_uint_t)gc_pool_start) / BYTES_PER_BLOCK)
#define PTR_FROM_BLOCK(block) (((block) * BYTES_PER_BLOCK + (machine_uint_t)gc_pool_start))
#define ATB_FROM_BLOCK(bl) ((bl) / BLOCKS_PER_ATB)
#if MICROPY_ENABLE_FINALISER
// FTB = finaliser table byte
// if set, then the corresponding block may have a finaliser
#define BLOCKS_PER_FTB (8)
#define FTB_GET(block) ((gc_finaliser_table_start[(block) / BLOCKS_PER_FTB] >> ((block) & 7)) & 1)
#define FTB_SET(block) do { gc_finaliser_table_start[(block) / BLOCKS_PER_FTB] |= (1 << ((block) & 7)); } while (0)
#define FTB_CLEAR(block) do { gc_finaliser_table_start[(block) / BLOCKS_PER_FTB] &= (~(1 << ((block) & 7))); } while (0)
#endif
// TODO waste less memory; currently requires that all entries in alloc_table have a corresponding block in pool
void gc_init(void *start, void *end) {
// align end pointer on block boundary
end = (void*)((machine_uint_t)end & (~(BYTES_PER_BLOCK - 1)));
DEBUG_printf("Initializing GC heap: %p-%p\n", start, end);
DEBUG_printf("Initializing GC heap: %p..%p = %ld bytes\n", start, end, end - start);
// calculate parameters for GC (T=total, A=alloc table, F=finaliser table, P=pool; all in bytes):
// T = A + F + P
// F = A * BLOCKS_PER_ATB / BLOCKS_PER_FTB
// P = A * BLOCKS_PER_ATB * BYTES_PER_BLOCK
// => T = A * (1 + BLOCKS_PER_ATB / BLOCKS_PER_FTB + BLOCKS_PER_ATB * BYTES_PER_BLOCK)
machine_uint_t total_byte_len = end - start;
#if MICROPY_ENABLE_FINALISER
gc_alloc_table_byte_len = total_byte_len * BITS_PER_BYTE / (BITS_PER_BYTE + BITS_PER_BYTE * BLOCKS_PER_ATB / BLOCKS_PER_FTB + BITS_PER_BYTE * BLOCKS_PER_ATB * BYTES_PER_BLOCK);
#else
gc_alloc_table_byte_len = total_byte_len / (1 + BITS_PER_BYTE / 2 * BYTES_PER_BLOCK);
#endif
// calculate parameters for GC
machine_uint_t total_word_len = (machine_uint_t*)end - (machine_uint_t*)start;
gc_alloc_table_byte_len = total_word_len * BYTES_PER_WORD / (1 + BITS_PER_BYTE / 2 * BYTES_PER_BLOCK);
gc_alloc_table_start = (byte*)start;
gc_mpobj_table_byte_len = (gc_alloc_table_byte_len * BITS_PER_BYTE / 2)/8;
gc_mpobj_table_start = gc_alloc_table_start+gc_alloc_table_byte_len;
#if MICROPY_ENABLE_FINALISER
machine_uint_t gc_finaliser_table_byte_len = (gc_alloc_table_byte_len * BLOCKS_PER_ATB) / BLOCKS_PER_FTB;
gc_finaliser_table_start = gc_alloc_table_start + gc_alloc_table_byte_len;
#endif
machine_uint_t gc_pool_block_len = (gc_alloc_table_byte_len * BITS_PER_BYTE / 2) -(gc_mpobj_table_byte_len / BYTES_PER_BLOCK);
machine_uint_t gc_pool_word_len = gc_pool_block_len * WORDS_PER_BLOCK;
gc_pool_start = (machine_uint_t*)end - gc_pool_word_len;
machine_uint_t gc_pool_block_len = gc_alloc_table_byte_len * BLOCKS_PER_ATB;
gc_pool_start = end - gc_pool_block_len * BYTES_PER_BLOCK;
gc_pool_end = end;
// clear ATBs
memset(gc_alloc_table_start, 0, gc_alloc_table_byte_len);
// clear MPOBJ flags
memset(gc_mpobj_table_start, 0, gc_mpobj_table_byte_len);
#if MICROPY_ENABLE_FINALISER
// clear FTBs
memset(gc_finaliser_table_start, 0, gc_finaliser_table_byte_len);
#endif
// allocate first block because gc_pool_start points there and it will never
// be freed, so allocating 1 block with null pointers will minimise memory loss
@ -107,9 +129,15 @@ void gc_init(void *start, void *end) {
gc_pool_start[i] = 0;
}
// unlock the GC
gc_lock = false;
DEBUG_printf("GC layout:\n");
DEBUG_printf(" alloc table at %p, length " UINT_FMT " bytes\n", gc_alloc_table_start, gc_alloc_table_byte_len);
DEBUG_printf(" pool at %p, length " UINT_FMT " blocks = " UINT_FMT " words = " UINT_FMT " bytes\n", gc_pool_start, gc_pool_block_len, gc_pool_word_len, gc_pool_word_len * BYTES_PER_WORD);
DEBUG_printf(" alloc table at %p, length " UINT_FMT " bytes, " UINT_FMT " blocks\n", gc_alloc_table_start, gc_alloc_table_byte_len, gc_alloc_table_byte_len * BLOCKS_PER_ATB);
#if MICROPY_ENABLE_FINALISER
DEBUG_printf(" finaliser table at %p, length " UINT_FMT " bytes, " UINT_FMT " blocks\n", gc_finaliser_table_start, gc_finaliser_table_byte_len, gc_finaliser_table_byte_len * BLOCKS_PER_FTB);
#endif
DEBUG_printf(" pool at %p, length " UINT_FMT " bytes, " UINT_FMT " blocks\n", gc_pool_start, gc_pool_block_len * BYTES_PER_BLOCK, gc_pool_block_len);
}
#define VERIFY_PTR(ptr) ( \
@ -176,16 +204,22 @@ STATIC void gc_sweep(void) {
for (machine_uint_t block = 0; block < gc_alloc_table_byte_len * BLOCKS_PER_ATB; block++) {
switch (ATB_GET_KIND(block)) {
case AT_HEAD:
if (ATB_IS_MPOBJ(block)) {
mp_obj_t dest[2];
mp_load_method((mp_obj_t*)PTR_FROM_BLOCK(block), MP_QSTR___del__, dest);
// load_method returned a method
if (dest[1] != MP_OBJ_NULL) {
mp_call_method_n_kw(0, 0, dest);
#if MICROPY_ENABLE_FINALISER
if (FTB_GET(block)) {
mp_obj_t obj = (mp_obj_t)PTR_FROM_BLOCK(block);
if (((mp_obj_base_t*)obj)->type != MP_OBJ_NULL) {
// if the object has a type then see if it has a __del__ method
mp_obj_t dest[2];
mp_load_method_maybe(obj, MP_QSTR___del__, dest);
if (dest[0] != MP_OBJ_NULL) {
// load_method returned a method
mp_call_method_n_kw(0, 0, dest);
}
}
// clear mpobj flag
ATB_CLR_MPOBJ(block);
// clear finaliser flag
FTB_CLEAR(block);
}
#endif
free_tail = 1;
// fall through to free the head
@ -204,6 +238,7 @@ STATIC void gc_sweep(void) {
}
void gc_collect_start(void) {
gc_lock = true;
gc_stack_overflow = 0;
gc_sp = gc_stack;
}
@ -219,6 +254,7 @@ void gc_collect_root(void **ptrs, machine_uint_t len) {
void gc_collect_end(void) {
gc_deal_with_stack_overflow();
gc_sweep();
gc_lock = false;
}
void gc_info(gc_info_t *info) {
@ -266,10 +302,14 @@ void gc_info(gc_info_t *info) {
info->free *= BYTES_PER_BLOCK;
}
void *_gc_alloc(machine_uint_t n_bytes, bool is_mpobj) {
void *gc_alloc(machine_uint_t n_bytes, bool has_finaliser) {
machine_uint_t n_blocks = ((n_bytes + BYTES_PER_BLOCK - 1) & (~(BYTES_PER_BLOCK - 1))) / BYTES_PER_BLOCK;
DEBUG_printf("gc_alloc(" UINT_FMT " bytes -> " UINT_FMT " blocks)\n", n_bytes, n_blocks);
if (gc_lock) {
// TODO
}
// check for 0 allocation
if (n_blocks == 0) {
return NULL;
@ -315,25 +355,37 @@ found:
ATB_FREE_TO_TAIL(bl);
}
if (is_mpobj) {
// set mp_obj flag only if it has del
ATB_SET_MPOBJ(start_block);
}
// get pointer to first block
void *ret_ptr = (void*)(gc_pool_start + start_block * WORDS_PER_BLOCK);
// return pointer to first block
return (void*)(gc_pool_start + start_block * WORDS_PER_BLOCK);
#if MICROPY_ENABLE_FINALISER
if (has_finaliser) {
// clear type pointer in case it is never set
((mp_obj_base_t*)ret_ptr)->type = MP_OBJ_NULL;
// set mp_obj flag only if it has a finaliser
FTB_SET(start_block);
}
#endif
return ret_ptr;
}
/*
void *gc_alloc(machine_uint_t n_bytes) {
return _gc_alloc(n_bytes, false);
}
void *gc_alloc_mp_obj(machine_uint_t n_bytes) {
void *gc_alloc_with_finaliser(machine_uint_t n_bytes) {
return _gc_alloc(n_bytes, true);
}
*/
// force the freeing of a piece of memory
void gc_free(void *ptr_in) {
if (gc_lock) {
// TODO
}
machine_uint_t ptr = (machine_uint_t)ptr_in;
if (VERIFY_PTR(ptr)) {
@ -386,12 +438,16 @@ void *gc_realloc(void *ptr, machine_uint_t n_bytes) {
}
#else
void *gc_realloc(void *ptr_in, machine_uint_t n_bytes) {
if (gc_lock) {
// TODO
}
void *ptr_out = NULL;
machine_uint_t block = 0;
machine_uint_t ptr = (machine_uint_t)ptr_in;
if (ptr_in == NULL) {
return gc_alloc(n_bytes);
return gc_alloc(n_bytes, false);
}
if (VERIFY_PTR(ptr) // verify pointer
@ -444,7 +500,13 @@ void *gc_realloc(void *ptr_in, machine_uint_t n_bytes) {
ptr_out = ptr_in;
// try to find a new contiguous chain
} else if ((ptr_out = gc_alloc(n_bytes)) != NULL) {
} else if ((ptr_out = gc_alloc(n_bytes,
#if MICROPY_ENABLE_FINALISER
FTB_GET(block)
#else
false
#endif
)) != NULL) {
DEBUG_printf("gc_realloc: allocating new block\n");
memcpy(ptr_out, ptr_in, n_existing);
gc_free(ptr_in);
@ -489,18 +551,18 @@ void gc_test(void) {
gc_init(heap, heap + len / sizeof(machine_uint_t));
void *ptrs[100];
{
machine_uint_t **p = gc_alloc(16);
p[0] = gc_alloc(64);
p[1] = gc_alloc(1);
p[2] = gc_alloc(1);
p[3] = gc_alloc(1);
machine_uint_t ***p2 = gc_alloc(16);
machine_uint_t **p = gc_alloc(16, false);
p[0] = gc_alloc(64, false);
p[1] = gc_alloc(1, false);
p[2] = gc_alloc(1, false);
p[3] = gc_alloc(1, false);
machine_uint_t ***p2 = gc_alloc(16, false);
p2[0] = p;
p2[1] = p;
ptrs[0] = p2;
}
for (int i = 0; i < 25; i+=2) {
machine_uint_t *p = gc_alloc(i);
machine_uint_t *p = gc_alloc(i, false);
printf("p=%p\n", p);
if (i & 3) {
//ptrs[i] = p;

3
py/gc.h
View File

@ -3,8 +3,7 @@ void gc_collect_start(void);
void gc_collect_root(void **ptrs, machine_uint_t len);
void gc_collect_end(void);
void gc_collect(void);
void *gc_alloc(machine_uint_t n_bytes);
void *gc_alloc_mp_obj(machine_uint_t n_bytes);
void *gc_alloc(machine_uint_t n_bytes, bool has_finaliser);
void gc_free(void *ptr);
machine_uint_t gc_nbytes(void *ptr);
void *gc_realloc(void *ptr, machine_uint_t n_bytes);

13
py/malloc.c
View File

@ -30,8 +30,8 @@ STATIC int peak_bytes_allocated = 0;
#undef malloc
#undef free
#undef realloc
#define malloc gc_alloc
#define malloc_mp_obj gc_alloc_mp_obj
#define malloc(b) gc_alloc((b), false)
#define malloc_with_finaliser(b) gc_alloc((b), true)
#define free gc_free
#define realloc gc_realloc
#endif // MICROPY_ENABLE_GC
@ -53,14 +53,14 @@ void *m_malloc(int num_bytes) {
return ptr;
}
void *m_malloc_mp_obj(int num_bytes) {
#if MICROPY_ENABLE_FINALISER
void *m_malloc_with_finaliser(int num_bytes) {
if (num_bytes == 0) {
return NULL;
}
void *ptr = malloc_mp_obj(num_bytes);
void *ptr = malloc_with_finaliser(num_bytes);
if (ptr == NULL) {
printf("could not allocate memory, allocating %d bytes\n", num_bytes);
return NULL;
return m_malloc_fail(num_bytes);
}
#if MICROPY_MEM_STATS
total_bytes_allocated += num_bytes;
@ -70,6 +70,7 @@ void *m_malloc_mp_obj(int num_bytes) {
DEBUG_printf("malloc %d : %p\n", num_bytes, ptr);
return ptr;
}
#endif
void *m_malloc0(int num_bytes) {
void *ptr = m_malloc(num_bytes);

8
py/misc.h
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@ -27,14 +27,18 @@ typedef unsigned int uint;
#define m_new0(type, num) ((type*)(m_malloc0(sizeof(type) * (num))))
#define m_new_obj(type) (m_new(type, 1))
#define m_new_obj_var(obj_type, var_type, var_num) ((obj_type*)m_malloc(sizeof(obj_type) + sizeof(var_type) * (var_num)))
#define m_new_mp_obj(type)((type*)(m_malloc_mp_obj(sizeof(type))))
#if MICROPY_ENABLE_FINALISER
#define m_new_obj_with_finaliser(type) ((type*)(m_malloc_with_finaliser(sizeof(type))))
#else
#define m_new_obj_with_finaliser(type) m_new_obj(type)
#endif
#define m_renew(type, ptr, old_num, new_num) ((type*)(m_realloc((ptr), sizeof(type) * (old_num), sizeof(type) * (new_num))))
#define m_del(type, ptr, num) m_free(ptr, sizeof(type) * (num))
#define m_del_obj(type, ptr) (m_del(type, ptr, 1))
#define m_del_var(obj_type, var_type, var_num, ptr) (m_free(ptr, sizeof(obj_type) + sizeof(var_type) * (var_num)))
void *m_malloc(int num_bytes);
void *m_malloc_mp_obj(int num_bytes);
void *m_malloc_with_finaliser(int num_bytes);
void *m_malloc0(int num_bytes);
void *m_realloc(void *ptr, int old_num_bytes, int new_num_bytes);
void m_free(void *ptr, int num_bytes);

5
py/mpconfig.h
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@ -55,6 +55,11 @@
#define MICROPY_ENABLE_GC (0)
#endif
// Whether to enable finalisers in the garbage collector (ie call __del__)
#ifndef MICROPY_ENABLE_GC_FINALISER
#define MICROPY_ENABLE_GC_FINALISER (0)
#endif
// Whether to include REPL helper function
#ifndef MICROPY_ENABLE_REPL_HELPERS
#define MICROPY_ENABLE_REPL_HELPERS (0)

2
stm/file.c
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@ -71,7 +71,7 @@ static const mp_obj_type_t file_obj_type = {
mp_obj_t pyb_io_open(mp_obj_t o_filename, mp_obj_t o_mode) {
const char *filename = mp_obj_str_get_str(o_filename);
const char *mode = mp_obj_str_get_str(o_mode);
pyb_file_obj_t *self = m_new_mp_obj(pyb_file_obj_t);
pyb_file_obj_t *self = m_new_obj_with_finaliser(pyb_file_obj_t);
self->base.type = &file_obj_type;
if (mode[0] == 'r') {
// open for reading

3
stm/malloc0.c
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@ -1,5 +1,6 @@
#include <stdio.h>
#include <stdint.h>
#include "std.h"
#include "misc.h"
#include "mpconfig.h"
#include "gc.h"

1
stm/mpconfigport.h
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@ -5,6 +5,7 @@
#define MICROPY_EMIT_THUMB (1)
#define MICROPY_EMIT_INLINE_THUMB (1)
#define MICROPY_ENABLE_GC (1)
#define MICROPY_ENABLE_FINALISER (1)
#define MICROPY_ENABLE_REPL_HELPERS (1)
#define MICROPY_LONGINT_IMPL (MICROPY_LONGINT_IMPL_MPZ)
#define MICROPY_FLOAT_IMPL (MICROPY_FLOAT_IMPL_FLOAT)

3
stmhal/file.c
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@ -53,6 +53,7 @@ STATIC const mp_map_elem_t file_locals_dict_table[] = {
{ MP_OBJ_NEW_QSTR(MP_QSTR_readline), (mp_obj_t)&mp_stream_unbuffered_readline_obj},
{ MP_OBJ_NEW_QSTR(MP_QSTR_write), (mp_obj_t)&mp_stream_write_obj },
{ MP_OBJ_NEW_QSTR(MP_QSTR_close), (mp_obj_t)&file_obj_close_obj },
{ MP_OBJ_NEW_QSTR(MP_QSTR___del__), (mp_obj_t)&file_obj_close_obj },
{ MP_OBJ_NEW_QSTR(MP_QSTR___enter__), (mp_obj_t)&mp_identity_obj },
{ MP_OBJ_NEW_QSTR(MP_QSTR___exit__), (mp_obj_t)&file_obj___exit___obj },
};
@ -81,7 +82,7 @@ STATIC mp_obj_t file_obj_make_new(mp_obj_t type_in, uint n_args, uint n_kw, cons
if (n_args > 1) {
mode = mp_obj_str_get_str(args[1]);
}
pyb_file_obj_t *self = m_new_obj(pyb_file_obj_t);
pyb_file_obj_t *self = m_new_obj_with_finaliser(pyb_file_obj_t);
self->base.type = &file_obj_type;
if (mode[0] == 'r') {
// open for reading

3
stmhal/malloc0.c
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@ -1,5 +1,6 @@
#include <stdio.h>
#include <stdint.h>
#include "std.h"
#include "misc.h"
#include "mpconfig.h"
#include "gc.h"

1
stmhal/mpconfigport.h
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@ -5,6 +5,7 @@
#define MICROPY_EMIT_THUMB (1)
#define MICROPY_EMIT_INLINE_THUMB (1)
#define MICROPY_ENABLE_GC (1)
#define MICROPY_ENABLE_FINALISER (1)
#define MICROPY_ENABLE_REPL_HELPERS (1)
#define MICROPY_LONGINT_IMPL (MICROPY_LONGINT_IMPL_MPZ)
#define MICROPY_FLOAT_IMPL (MICROPY_FLOAT_IMPL_FLOAT)

1
unix/mpconfigport.h
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@ -4,6 +4,7 @@
#define MICROPY_EMIT_THUMB (0)
#define MICROPY_EMIT_INLINE_THUMB (0)
#define MICROPY_ENABLE_GC (1)
#define MICROPY_ENABLE_FINALISER (1)
#define MICROPY_MEM_STATS (1)
#define MICROPY_DEBUG_PRINTERS (1)
#define MICROPY_ENABLE_REPL_HELPERS (1)