From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] SNMPv2 tcpOutSegs counter error
Date: Thu, 03 Aug 2006 16:35:54 -0700 (PDT)
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From: Wei Yongjun <yjwei@nanjing-fnst.com>
Date: Thu, 03 Aug 2006 11:46:58 -0400

> I modified my patch by add a flag to sacked when retransmit, and it
> work well.

This is the most timing critical code path of the TCP stack output
packet processing, and you're adding a read-modify-write operation
just to get some statistics correct.

Let's look for a cheaper test, perhaps something like:

	if (!before(TCP_SKB_CB(skb)->seq, tp->snd_nxt))
		TCP_INC_STATS(TCP_MIB_OUTSEGS);

Would that work?

It should, because tp->snd_nxt always advances on new data
via update_send_head().