Function mi_region_try_claim

3rd/mimalloc-2.0.9/src/region.c:243–262

static bool mi_region_try_claim(int numa_node, size_t blocks, bool allow_large, mem_region_t** region, mi_bitmap_index_t* bit_idx, mi_os_tld_t* tld)
{
  // try all regions for a free slot
  const size_t count = mi_atomic_load_relaxed(&regions_count); // monotonic, so ok to be relaxed
  size_t idx = tld->region_idx; // Or start at 0 to reuse low addresses? Starting at 0 seems to increase latency though
  for (size_t visited = 0; visited < count; visited++, idx++) {
    if (idx >= count) idx = 0;  // wrap around
    mem_region_t* r = &regions[idx];
    // if this region suits our demand (numa node matches, large OS page matches)
    if (mi_region_is_suitable(r, numa_node, allow_large)) {
      // then try to atomically claim a segment(s) in this region
      if (_mi_bitmap_try_find_claim_field(&r->in_use, 0, blocks, bit_idx)) {
        tld->region_idx = idx;    // remember the last found position
        *region = r;
        return true;
      }
    }
  }
  return false;
}


static void* mi_region_try_alloc(size_t blocks, bool* commit, bool* large, bool* is_pinned, bool* is_zero, size_t* memid, mi_os_tld_t* tld)