diff options
Diffstat (limited to 'py')
| -rw-r--r-- | py/gc.c | 74 |
1 files changed, 64 insertions, 10 deletions
@@ -46,6 +46,9 @@ #define DEBUG_printf(...) (void)0 #endif +// make this 1 to dump the heap each time it changes +#define EXTENSIVE_HEAP_PROFILING (0) + #define WORDS_PER_BLOCK (4) #define BYTES_PER_BLOCK (WORDS_PER_BLOCK * BYTES_PER_WORD) #define STACK_SIZE (64) // tunable; minimum is 1 @@ -386,13 +389,6 @@ void *gc_alloc(mp_uint_t n_bytes, bool has_finaliser) { if (ATB_2_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 2; goto found; } } else { n_free = 0; } if (ATB_3_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 3; goto found; } } else { n_free = 0; } } - for (i = 0; i < gc_last_free_atb_index; i++) { - byte a = gc_alloc_table_start[i]; - if (ATB_0_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 0; goto found; } } else { n_free = 0; } - if (ATB_1_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 1; goto found; } } else { n_free = 0; } - if (ATB_2_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 2; goto found; } } else { n_free = 0; } - if (ATB_3_IS_FREE(a)) { if (++n_free >= n_blocks) { i = i * BLOCKS_PER_ATB + 3; goto found; } } else { n_free = 0; } - } // nothing found! if (collected) { @@ -409,8 +405,14 @@ found: end_block = i; start_block = i - n_free + 1; - // set last free ATB index to last block we found, for start of next scan - gc_last_free_atb_index = i / BLOCKS_PER_ATB; + // 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 shink a block we must check + // if this index needs adjusting (see gc_realloc and gc_free). + if (n_free == 1) { + gc_last_free_atb_index = (i + 1) / BLOCKS_PER_ATB; + } // mark first block as used head ATB_FREE_TO_HEAD(start_block); @@ -441,6 +443,10 @@ found: } #endif + #if EXTENSIVE_HEAP_PROFILING + gc_dump_alloc_table(); + #endif + return ret_ptr; } @@ -467,11 +473,20 @@ void gc_free(void *ptr_in) { if (VERIFY_PTR(ptr)) { mp_uint_t block = BLOCK_FROM_PTR(ptr); if (ATB_GET_KIND(block) == AT_HEAD) { + // set the last_free pointer to this block if it's earlier in the heap + if (block / BLOCKS_PER_ATB < gc_last_free_atb_index) { + gc_last_free_atb_index = block / BLOCKS_PER_ATB; + } + // free head and all of its tail blocks do { ATB_ANY_TO_FREE(block); block += 1; } while (ATB_GET_KIND(block) == AT_TAIL); + + #if EXTENSIVE_HEAP_PROFILING + gc_dump_alloc_table(); + #endif } } } @@ -583,6 +598,16 @@ void *gc_realloc(void *ptr_in, mp_uint_t n_bytes) { for (mp_uint_t bl = block + new_blocks; ATB_GET_KIND(bl) == AT_TAIL; bl++) { ATB_ANY_TO_FREE(bl); } + + // set the last_free pointer to end of this block if it's earlier in the heap + if ((block + new_blocks) / BLOCKS_PER_ATB < gc_last_free_atb_index) { + gc_last_free_atb_index = (block + new_blocks) / BLOCKS_PER_ATB; + } + + #if EXTENSIVE_HEAP_PROFILING + gc_dump_alloc_table(); + #endif + return ptr_in; } @@ -597,6 +622,10 @@ void *gc_realloc(void *ptr_in, mp_uint_t n_bytes) { // zero out the additional bytes of the newly allocated blocks (see comment above in gc_alloc) memset((byte*)ptr_in + n_bytes, 0, new_blocks * BYTES_PER_BLOCK - n_bytes); + #if EXTENSIVE_HEAP_PROFILING + gc_dump_alloc_table(); + #endif + return ptr_in; } @@ -630,9 +659,34 @@ void gc_dump_info() { } void gc_dump_alloc_table(void) { + static const mp_uint_t DUMP_BYTES_PER_LINE = 64; + #if !EXTENSIVE_HEAP_PROFILING + // When comparing heap output we don't want to print the starting + // pointer of the heap because it changes from run to run. printf("GC memory layout; from %p:", gc_pool_start); + #endif for (mp_uint_t bl = 0; bl < gc_alloc_table_byte_len * BLOCKS_PER_ATB; bl++) { - if (bl % 64 == 0) { + if (bl % DUMP_BYTES_PER_LINE == 0) { + // a new line of blocks + #if EXTENSIVE_HEAP_PROFILING + { + // check if this line contains only free blocks + bool only_free_blocks = true; + for (mp_uint_t bl2 = bl; bl2 < gc_alloc_table_byte_len * BLOCKS_PER_ATB && bl2 < bl + DUMP_BYTES_PER_LINE; bl2++) { + if (ATB_GET_KIND(bl2) != AT_FREE) { + + only_free_blocks = false; + break; + } + } + if (only_free_blocks) { + // line contains only free blocks, so skip printing it + bl += DUMP_BYTES_PER_LINE - 1; + continue; + } + } + #endif + // print header for new line of blocks printf("\n%04x: ", (uint)bl); } int c = ' '; |