From: Li Yu <raise.sail@gmail.com>
To: Neal Cardwell <ncardwell@google.com>
Cc: netdev@vger.kernel.org
Subject: Re: [PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss()
Date: Wed, 28 Mar 2012 14:54:01 +0800 [thread overview]
Message-ID: <4F72B589.5060903@gmail.com> (raw)
In-Reply-To: <CADVnQymQaCSKx0aRda6OiP=t2OToxHmvjXjYvTdxsq7oFE3DTg@mail.gmail.com>
于 2012年03月28日 13:29, Neal Cardwell 写道:
> On Wed, Mar 28, 2012 at 12:23 AM, Li Yu<raise.sail@gmail.com> wrote:
>>
>> It seem that we forget remove below two lines after copying code :)
>>
>> This update never impacts others.
>
> The 'flag' variable will be used in later iterations of the
> tcp_for_write_queue() loop. The comment seems to quite sensibly
> indicate that the FLAG_DATA_ACKED bit is being set to avoid entering
> that branch of the if statement in later segments in the loop:
>
> 2168 if ((tp->frto_counter == 1)&& !(flag& FLAG_DATA_ACKED)) {
> 2169 /* For some reason this R-bit might get cleared? */
> 2170 if (TCP_SKB_CB(skb)->sacked& TCPCB_SACKED_RETRANS)
> 2171 tp->retrans_out += tcp_skb_pcount(skb);
> 2172 /* ...enter this if branch just for the
> first segment */
> 2173 flag |= FLAG_DATA_ACKED;
> 2174 } else {
>
> The structure of the logic seems intact from the original commit that
> added this:
>
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=d1a54c6a0a3f9c2c4ef71982d89b8571bd9eaa51
>
Sorry for spent time on this, it it account for F-RTO retransmitted
segment here.
Yu
> neal
>
next prev parent reply other threads:[~2012-03-28 6:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-28 4:23 [PATCH] tcp: remove useless update for flag parameter in tcp_enter_frto_loss() Li Yu
2012-03-28 5:27 ` Yuchung Cheng
2012-03-28 5:29 ` Neal Cardwell
2012-03-28 6:54 ` Li Yu [this message]
2012-03-28 7:34 ` Eric Dumazet
-- strict thread matches above, loose matches on Subject: below --
2012-03-28 4:00 Li Yu
2012-03-28 4:17 ` David Miller
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