From: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>
To: Nandita Dukkipati <nanditad@google.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Netdev <netdev@vger.kernel.org>,
Tom Herbert <therbert@google.com>,
Matt Mathis <mattmathis@google.com>,
Yuchung Cheng <ycheng@google.com>
Subject: Re: [PATCH v2] Proportional Rate Reduction for TCP.
Date: Sat, 20 Aug 2011 15:41:36 +0300 (EEST) [thread overview]
Message-ID: <alpine.DEB.2.00.1108201534590.24318@melkinpaasi.cs.helsinki.fi> (raw)
In-Reply-To: <CAB_+Fg4z46iLv29jX6dXK6GSBbnPxWroq99V6Yr25vpCYrJBqw@mail.gmail.com>
[-- Attachment #1: Type: TEXT/PLAIN, Size: 1430 bytes --]
On Fri, 19 Aug 2011, Nandita Dukkipati wrote:
> Forgot to turn off gmail's rich formatting, so re-sending to the list.
>
> On Fri, Aug 19, 2011 at 3:25 AM, Ilpo Järvinen
> <ilpo.jarvinen@helsinki.fi> wrote:
> >
> > On Fri, 19 Aug 2011, Nandita Dukkipati wrote:
> >
> > > +static void tcp_update_cwnd_in_recovery(struct sock *sk, int newly_acked_sacked,
> > > + int fast_rexmit, int flag)
> > > +{
> > > + struct tcp_sock *tp = tcp_sk(sk);
> > > + int sndcnt = 0;
> > > + int delta = tp->snd_ssthresh - tcp_packets_in_flight(tp);
> > > +
> > > + if (tcp_packets_in_flight(tp) > tp->snd_ssthresh) {
> > > + if (WARN_ON(!tp->prior_cwnd))
> > > + tp->prior_cwnd = 1;
> >
> > This should still be made larger to avoid problems if it ever will be
> > needed.
>
> I am letting the value remain at 1, mainly because this is the valid
> lowest non-zero value for snd_cwnd to take on. The main purpose of
> this code is to catch any lurking bug outside of PRR which results in
> an undesirable divide by 0 in PRR. I would like to fix that bug if I
> find this code is executed.
NACK, until this value is at least 2 * tp->snd_ssthresh. Or alternatively
the fallback is removed so that we DBZ and do not end up wrecking the
network.
Other than that I'm ok with the patch (assuming the branches I brought
up earlier is ok for everybody else).
--
i.
next prev parent reply other threads:[~2011-08-20 12:41 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-12 7:29 [PATCH] Proportional Rate Reduction for TCP Nandita Dukkipati
2011-08-12 11:36 ` Ilpo Järvinen
2011-08-19 7:34 ` Nandita Dukkipati
2011-08-14 5:05 ` Andi Kleen
2011-08-19 7:34 ` Nandita Dukkipati
2011-08-19 7:33 ` [PATCH v2] " Nandita Dukkipati
2011-08-19 10:25 ` Ilpo Järvinen
2011-08-20 1:28 ` Nandita Dukkipati
2011-08-20 12:41 ` Ilpo Järvinen [this message]
2011-08-22 6:21 ` Nandita Dukkipati
2011-08-19 10:26 ` David Miller
2011-08-20 1:29 ` Nandita Dukkipati
2011-08-20 1:29 ` [PATCH v3] " Nandita Dukkipati
2011-08-22 6:21 ` [PATCH v4] " Nandita Dukkipati
2011-08-25 2:43 ` David Miller
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