From: Nandita Dukkipati <nanditad@google.com>
To: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>
Cc: "David S. Miller" <davem@davemloft.net>,
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: Fri, 19 Aug 2011 18:28:58 -0700 [thread overview]
Message-ID: <CAB_+Fg4z46iLv29jX6dXK6GSBbnPxWroq99V6Yr25vpCYrJBqw@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1108191312170.12780@wel-95.cs.helsinki.fi>
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.
>
> > + sndcnt = DIV_ROUND_UP((u64)(tp->prr_delivered *
> > + tp->snd_ssthresh),
> > + (u64)tp->prior_cwnd) - tp->prr_out;
>
> I think you should pick one from include/linux/math64.h instead of letting
> gcc to do / operand all by itself. ...Obviosly then the ROUND_UP part
> needs to be done manually (either using the remainder or pre-addition
> like DIV_ROUND_UP does).
Done. patch v3 used div_u64.
Thanks
Nandita
next prev parent reply other threads:[~2011-08-20 1:29 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 [this message]
2011-08-20 12:41 ` Ilpo Järvinen
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAB_+Fg4z46iLv29jX6dXK6GSBbnPxWroq99V6Yr25vpCYrJBqw@mail.gmail.com \
--to=nanditad@google.com \
--cc=davem@davemloft.net \
--cc=ilpo.jarvinen@helsinki.fi \
--cc=mattmathis@google.com \
--cc=netdev@vger.kernel.org \
--cc=therbert@google.com \
--cc=ycheng@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).