Priority ranges from 0 to 15 in increments of 4096: so 0 means 0 (lower priority = higher probability to become root), 1 = 4096 and so on up to 15 = 61440 [*]
[*] the sequence should be 0 4096 8192 12288 16384 20480 24576 28672 32768 36864 40960 45056 49152 53248 57344 61440.