zs_usage_compute
usage_print = zs_usage_compute(NULL, usage_last,
(void) zs_usage_compute(usage, ctl->zsctl_start, usage,
(void) zs_usage_compute(set->zsus_high, set->zsus_high, usage,
(void) zs_usage_compute(set->zsus_total, set->zsus_total, usage,
(void) zs_usage_compute(set->zsus_avg, set->zsus_avg, usage,
zs_usage_t *zs_usage_compute(zs_usage_t *, zs_usage_t *, zs_usage_t *, int);