BLKIOLATENCY_NR_EXP_FACTORS
(BLKIOLATENCY_NR_EXP_FACTORS - 1))
static const u64 iolatency_exp_factors[BLKIOLATENCY_NR_EXP_FACTORS] = {
exp_idx = min_t(int, BLKIOLATENCY_NR_EXP_FACTORS - 1,