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add good-fit for allowing larger blocks in smaller segments

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This commit is contained in:
daan 2019-08-09 11:18:38 -07:00
parent 5e56b40fe6
commit 442bad9190
7 changed files with 214 additions and 35 deletions
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11
src/page-queue.c
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@ -97,7 +97,7 @@ uint8_t _mi_bsr(uintptr_t x) {
// Returns MI_BIN_HUGE if the size is too large.
// We use `wsize` for the size in "machine word sizes",
// i.e. byte size == `wsize*sizeof(void*)`.
inline uint8_t _mi_bin(size_t size) {
extern inline uint8_t _mi_bin(size_t size) {
size_t wsize = _mi_wsize_from_size(size);
uint8_t bin;
if (wsize <= 1) {
@ -120,16 +120,21 @@ inline uint8_t _mi_bin(size_t size) {
bin = MI_BIN_HUGE;
}
else {
#if defined(MI_ALIGN4W)
#if defined(MI_ALIGN4W)
if (wsize <= 16) { wsize = (wsize+3)&~3; } // round to 4x word sizes
#endif
#ifdef MI_BIN4
uint8_t b = mi_bsr32((uint32_t)wsize);
bin = ((b << 1) + (uint8_t)((wsize >> (b - 1)) & 0x01)) + 3;
#else
wsize--;
// find the highest bit
uint8_t b = mi_bsr32((uint32_t)wsize);
// and use the top 3 bits to determine the bin (~16% worst internal fragmentation).
// and use the top 3 bits to determine the bin (~12.5% worst internal fragmentation).
// - adjust with 3 because we use do not round the first 8 sizes
// which each get an exact bin
bin = ((b << 2) + (uint8_t)((wsize >> (b - 2)) & 0x03)) - 3;
#endif
}
mi_assert_internal(bin > 0 && bin <= MI_BIN_HUGE);
return bin;