netdev - Re: [PATCH v2] Proportional Rate Reduction for TCP.

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Date:	Fri, 19 Aug 2011 18:29:15 -0700
From:	Nandita Dukkipati <nanditad@...gle.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, therbert@...gle.com, mattmathis@...gle.com,
	ycheng@...gle.com
Subject: Re: [PATCH v2] Proportional Rate Reduction for TCP.

On Fri, Aug 19, 2011 at 3:26 AM, David Miller <davem@...emloft.net> wrote:
> From: Nandita Dukkipati <nanditad@...gle.com>
> Date: Fri, 19 Aug 2011 00:33:32 -0700
>
>> @@ -2830,9 +2830,14 @@ static int tcp_try_undo_loss(struct sock *sk)
>>  static inline void tcp_complete_cwr(struct sock *sk)
>>  {
>>       struct tcp_sock *tp = tcp_sk(sk);
>> -     /* Do not moderate cwnd if it's already undone in cwr or recovery */
>> -     if (tp->undo_marker && tp->snd_cwnd > tp->snd_ssthresh) {
>> -             tp->snd_cwnd = tp->snd_ssthresh;
>> +
>> +     /* Do not moderate cwnd if it's already undone in cwr or recovery. */
>> +     if (tp->undo_marker) {
>> +
>> +             if (inet_csk(sk)->icsk_ca_state == TCP_CA_CWR)
>
> Please get rid of that empty line before the TCP_CA_CWR case.

Done.
>
>> +             sndcnt = DIV_ROUND_UP((u64)(tp->prr_delivered *
>> +                                         tp->snd_ssthresh),
>> +                                   (u64)tp->prior_cwnd) - tp->prr_out;
>
> This won't link on 32-bit unless __divdi3 libgcc routine is provided
> by the architecture.  To portably do 64-bit division you need to use
> do_div() or something based upon it.  Perhaps DIV_ROUND_UP_LL() will
> work best in this case.

patch v3 uses div_u64 which is based on do_div() for 32-bit archs.

Thanks
Nandita
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