diff options
Diffstat (limited to 'Objects/floatobject.c')
| -rw-r--r-- | Objects/floatobject.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/Objects/floatobject.c b/Objects/floatobject.c index 9f94003184..a2c281eaf8 100644 --- a/Objects/floatobject.c +++ b/Objects/floatobject.c @@ -21,7 +21,22 @@ extern int finite(double); #endif -/* Special free list -- see comments for same code in intobject.c. */ +/* Special free list + + Since some Python programs can spend much of their time allocating + and deallocating floats, these operations should be very fast. + Therefore we use a dedicated allocation scheme with a much lower + overhead (in space and time) than straight malloc(): a simple + dedicated free list, filled when necessary with memory from malloc(). + + block_list is a singly-linked list of all PyFloatBlocks ever allocated, + linked via their next members. PyFloatBlocks are never returned to the + system before shutdown (PyFloat_Fini). + + free_list is a singly-linked list of available PyFloatObjects, linked + via abuse of their ob_type members. +*/ + #define BLOCK_SIZE 1000 /* 1K less typical malloc overhead */ #define BHEAD_SIZE 8 /* Enough for a 64-bit pointer */ #define N_FLOATOBJECTS ((BLOCK_SIZE - BHEAD_SIZE) / sizeof(PyFloatObject)) |