some issues about ngx_http_upstream_fair_sched_score

[fankeke]

so why don't use the peer->shared-nreq as score directly to determine best_peer?
I can't see reason why using sched_socre function
becasuse the more nreq peer gets ,the high socre it gets.

besides,the what does the req_delta denote?
all back-end servers cur-connection or other(except this peer) servers cur-connection?

thanks