Track first free atb for multiple block sizes.

This speeds up cases where no single block allocations happen while
Python code is allocating other block sizes.
crypto-aes
Scott Shawcroft 3 years ago
parent a4d197a6ef
commit 36e6cc8feb
No known key found for this signature in database
GPG Key ID: 9349BC7E64B1921E

@ -150,9 +150,13 @@ void gc_init(void *start, void *end) {
#endif
// Set first free ATB index to the start of the heap.
MP_STATE_MEM(gc_first_free_atb_index) = 0;
for (size_t i = 0; i < MICROPY_ATB_INDICES; i++) {
MP_STATE_MEM(gc_first_free_atb_index)[i] = 0;
}
// Set last free ATB index to the end of the heap.
MP_STATE_MEM(gc_last_free_atb_index) = MP_STATE_MEM(gc_alloc_table_byte_len) - 1;
// Set the lowest long lived ptr to the end of the heap to start. This will be lowered as long
// lived objects are allocated.
MP_STATE_MEM(gc_lowest_long_lived_ptr) = (void*) PTR_FROM_BLOCK(MP_STATE_MEM(gc_alloc_table_byte_len * BLOCKS_PER_ATB));
@ -387,7 +391,9 @@ void gc_collect_root(void **ptrs, size_t len) {
void gc_collect_end(void) {
gc_deal_with_stack_overflow();
gc_sweep();
MP_STATE_MEM(gc_first_free_atb_index) = 0;
for (size_t i = 0; i < MICROPY_ATB_INDICES; i++) {
MP_STATE_MEM(gc_first_free_atb_index)[i] = 0;
}
MP_STATE_MEM(gc_last_free_atb_index) = MP_STATE_MEM(gc_alloc_table_byte_len) - 1;
MP_STATE_MEM(gc_lock_depth)--;
GC_EXIT();
@ -513,14 +519,16 @@ void *gc_alloc(size_t n_bytes, bool has_finaliser, bool long_lived) {
size_t crossover_block = BLOCK_FROM_PTR(MP_STATE_MEM(gc_lowest_long_lived_ptr));
while (keep_looking) {
int8_t direction = 1;
size_t start = MP_STATE_MEM(gc_first_free_atb_index);
size_t bucket = MIN(n_blocks, MICROPY_ATB_INDICES) - 1;
size_t first_free = MP_STATE_MEM(gc_first_free_atb_index)[bucket];
size_t start = first_free;
if (long_lived) {
direction = -1;
start = MP_STATE_MEM(gc_last_free_atb_index);
}
n_free = 0;
// look for a run of n_blocks available blocks
for (size_t i = start; keep_looking && MP_STATE_MEM(gc_first_free_atb_index) <= i && i <= MP_STATE_MEM(gc_last_free_atb_index); i += direction) {
for (size_t i = start; keep_looking && first_free <= i && i <= MP_STATE_MEM(gc_last_free_atb_index); i += direction) {
byte a = MP_STATE_MEM(gc_alloc_table_start)[i];
// Four ATB states are packed into a single byte.
int j = 0;
@ -565,22 +573,24 @@ void *gc_alloc(size_t n_bytes, bool has_finaliser, bool long_lived) {
// Found free space ending at found_block inclusive.
// Also, set last free ATB index to block after last block we found, for start of
// next scan. To reduce fragmentation, we only do this if we were looking
// for a single free block, which guarantees that there are no free blocks
// before this one. Also, whenever we free or shrink a block we must check
// if this index needs adjusting (see gc_realloc and gc_free).
// next scan. Also, whenever we free or shrink a block we must check if this index needs
// adjusting (see gc_realloc and gc_free).
if (!long_lived) {
end_block = found_block;
start_block = found_block - n_free + 1;
if (n_blocks == 1) {
MP_STATE_MEM(gc_first_free_atb_index) = (found_block + 1) / BLOCKS_PER_ATB;
if (n_blocks < MICROPY_ATB_INDICES) {
size_t next_free_atb = (found_block + n_blocks) / BLOCKS_PER_ATB;
// Update all atb indices for larger blocks too.
for (size_t i = n_blocks - 1; i < MICROPY_ATB_INDICES; i++) {
MP_STATE_MEM(gc_first_free_atb_index)[i] = next_free_atb;
}
}
} else {
start_block = found_block;
end_block = found_block + n_free - 1;
if (n_blocks == 1) {
MP_STATE_MEM(gc_last_free_atb_index) = (found_block - 1) / BLOCKS_PER_ATB;
}
// Always update the bounds of the long lived area because we assume it is contiguous. (It
// can still be reset by a sweep.)
MP_STATE_MEM(gc_last_free_atb_index) = (found_block - 1) / BLOCKS_PER_ATB;
}
#ifdef LOG_HEAP_ACTIVITY
@ -676,30 +686,37 @@ void gc_free(void *ptr) {
}
// get the GC block number corresponding to this pointer
assert(VERIFY_PTR(ptr));
size_t block = BLOCK_FROM_PTR(ptr);
assert(ATB_GET_KIND(block) == AT_HEAD);
size_t start_block = BLOCK_FROM_PTR(ptr);
assert(ATB_GET_KIND(start_block) == AT_HEAD);
#if MICROPY_ENABLE_FINALISER
FTB_CLEAR(block);
FTB_CLEAR(start_block);
#endif
// set the last_free pointer to this block if it's earlier in the heap
if (block / BLOCKS_PER_ATB < MP_STATE_MEM(gc_first_free_atb_index)) {
MP_STATE_MEM(gc_first_free_atb_index) = block / BLOCKS_PER_ATB;
}
if (block / BLOCKS_PER_ATB > MP_STATE_MEM(gc_last_free_atb_index)) {
MP_STATE_MEM(gc_last_free_atb_index) = block / BLOCKS_PER_ATB;
}
// free head and all of its tail blocks
#ifdef LOG_HEAP_ACTIVITY
gc_log_change(block, 0);
#endif
#ifdef LOG_HEAP_ACTIVITY
gc_log_change(start_block, 0);
#endif
size_t block = start_block;
do {
ATB_ANY_TO_FREE(block);
block += 1;
} while (ATB_GET_KIND(block) == AT_TAIL);
// Update the first free pointer for our size only. Not much calls gc_free directly so there
// is decent chance we'll want to allocate this size again. By only updating the specific
// size we don't risk something smaller fitting in.
size_t n_blocks = block - start_block;
size_t bucket = MIN(n_blocks, MICROPY_ATB_INDICES) - 1;
size_t new_free_atb = start_block / BLOCKS_PER_ATB;
if (new_free_atb < MP_STATE_MEM(gc_first_free_atb_index)[bucket]) {
MP_STATE_MEM(gc_first_free_atb_index)[bucket] = new_free_atb;
}
// set the last_free pointer to this block if it's earlier in the heap
if (new_free_atb > MP_STATE_MEM(gc_last_free_atb_index)) {
MP_STATE_MEM(gc_last_free_atb_index) = new_free_atb;
}
GC_EXIT();
#if EXTENSIVE_HEAP_PROFILING
@ -870,11 +887,13 @@ void *gc_realloc(void *ptr_in, size_t n_bytes, bool allow_move) {
}
// set the last_free pointer to end of this block if it's earlier in the heap
if ((block + new_blocks) / BLOCKS_PER_ATB < MP_STATE_MEM(gc_first_free_atb_index)) {
MP_STATE_MEM(gc_first_free_atb_index) = (block + new_blocks) / BLOCKS_PER_ATB;
size_t new_free_atb = (block + new_blocks) / BLOCKS_PER_ATB;
size_t bucket = MIN(n_blocks - new_blocks, MICROPY_ATB_INDICES) - 1;
if (new_free_atb < MP_STATE_MEM(gc_first_free_atb_index)[bucket]) {
MP_STATE_MEM(gc_first_free_atb_index)[bucket] = new_free_atb;
}
if ((block + new_blocks) / BLOCKS_PER_ATB > MP_STATE_MEM(gc_last_free_atb_index)) {
MP_STATE_MEM(gc_last_free_atb_index) = (block + new_blocks) / BLOCKS_PER_ATB;
if (new_free_atb > MP_STATE_MEM(gc_last_free_atb_index)) {
MP_STATE_MEM(gc_last_free_atb_index) = new_free_atb;
}
GC_EXIT();

@ -244,6 +244,14 @@
#define alloca(x) m_malloc(x)
#endif
// Number of atb indices to cache. Allocations of fewer blocks will be faster
// because the search will be accelerated by the index cache. This only applies
// to short lived allocations because we assume the long lived allocations are
// contiguous.
#ifndef MICROPY_ATB_INDICES
#define MICROPY_ATB_INDICES (8)
#endif
/*****************************************************************************/
/* MicroPython emitters */

@ -92,7 +92,7 @@ typedef struct _mp_state_mem_t {
size_t gc_alloc_threshold;
#endif
size_t gc_first_free_atb_index;
size_t gc_first_free_atb_index[MICROPY_ATB_INDICES];
size_t gc_last_free_atb_index;
#if MICROPY_PY_GC_COLLECT_RETVAL

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