Listing 1. Algorithm of MAT and ST Watermarks Heuristic

1 static int low_vm_enough_memory(long pages)
2 {
3   unsigned long committed;
4   unsigned long deny_threshold, notify_threshold;
5   int cap_sys_admin = 0;
6
7   if (cap_capable(current, CAP_SYS_ADMIN) == 0)
8     cap_sys_admin = 1;
9
10  if (deny_percentage==0||notify_percentage==0)
11    return __vm_enough_memory(pages,cap_sys_admin);
12
13  deny_threshold=
14       totalram_pages*deny_percentage/100;
15  notify_threshold=
16       totalram_pages*notify_percentage/ 100;
17
18      vm_acct_memory(pages);
19      committed = atomic_read(&vm_committed_space);
20      if (committed >= deny_threshold) {
21              enter_watermark_state(1);
22              if (cap_sys_admin)
23                      return 0;
24              vm_unacct_memory(pages);
25              return -ENOMEM;
26      } else if (committed >= notify_threshold) {
27              enter_watermark_state(1);
28              return 0;
29      }
30      enter_watermark_state(0);
31      return 0;
32 }