From: "Angelo P. Castellani" <angelo.castellani+lkml@gmail.com>
To: netdev <netdev@vger.kernel.org>
Cc: francesco@net.infocom.uniroma1.it, andrea.baiocchi@uniroma1.it
Subject: [PATCH] reno sacked_out count fix
Date: Tue, 16 May 2006 11:24:00 +0200 [thread overview]
Message-ID: <8dd26e70605160224i44bbaa8ei93eede75e71f6665@mail.gmail.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 611 bytes --]
Using NewReno, if a sk_buff is timed out and is accounted as lost_out,
it should also be removed from the sacked_out.
This is necessary because recovery using NewReno fast retransmit could
take up to a lot RTTs and the sk_buff RTO can expire without actually
being really lost.
left_out = sacked_out + lost_out
in_flight = packets_out - left_out + retrans_out
Using NewReno without this patch, on very large network losses,
left_out becames bigger than packets_out + retrans_out (!!).
For this reason unsigned integer in_flight overflows to 2^32 - something.
Regards,
Angelo P. Castellani
[-- Attachment #2: reno-fix.diff --]
[-- Type: text/x-patch, Size: 548 bytes --]
diff -urd ../linux-2.6.16-orig/net/ipv4/tcp_input.c ./net/ipv4/tcp_input.c
--- ../linux-2.6.16-orig/net/ipv4/tcp_input.c 2006-05-15 15:42:39.000000000 +0200
+++ ./net/ipv4/tcp_input.c 2006-05-16 11:18:21.000000000 +0200
@@ -1676,6 +1676,8 @@
if (!(TCP_SKB_CB(skb)->sacked&TCPCB_TAGBITS)) {
TCP_SKB_CB(skb)->sacked |= TCPCB_LOST;
tp->lost_out += tcp_skb_pcount(skb);
+ if (IsReno(tp))
+ tcp_remove_reno_sacks(sk, tp, tcp_skb_pcount(skb) + 1);
/* clear xmit_retrans hint */
if (tp->retransmit_skb_hint &&
next reply other threads:[~2006-05-16 9:24 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-16 9:24 Angelo P. Castellani [this message]
2006-05-17 4:40 ` [PATCH] reno sacked_out count fix David S. Miller
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