BUF_TRACKING_SIZE
i = bp->b_io_tcnt % BUF_TRACKING_SIZE;
for (j = 1; j <= BUF_TRACKING_SIZE; j++) {
#define BUF_TRACKING_ENTRY(x) ((x) & (BUF_TRACKING_SIZE - 1))
const char *b_io_tracking[BUF_TRACKING_SIZE];