LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Komuro <komurojun@nifty.com>
To: davem@sunset.davemloft.net
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [NOT VERY SAFE]     [TCP]: Set initial_ssthresh default to zero in Cubic and BIC.
Date: Sun, 14 Oct 2007 13:28:51 +0900	[thread overview]
Message-ID: <20071014132851.8d6a9de3.komurojun@nifty.com> (raw)
In-Reply-To: <20071014100245.914b784a.komurojun@nifty.com>


Dear David

>Komuro, every single email I sent to you bounces with "user unknown",
>I bet it is some spam filter or similar that doesn't like the
>fact that I lack reverse DNS.

>From mailing-list-archive,
I can read your email.

Best Regards
Komuro

> Dear David
> 
> Actually, tcp_sk(sk)->snd_ssthresh is not initialized,
> if initial_ssthresh is 0.
> 
> The patch should be
> 
>  static void bictcp_init(struct sock *sk)
>  {
>  	bictcp_reset(inet_csk_ca(sk));
> -	if (initial_ssthresh)
> -		tcp_sk(sk)->snd_ssthresh = initial_ssthresh;
> +
> +	tcp_sk(sk)->snd_ssthresh = initial_ssthresh;
>  }
> 
> Best Regards
> Komuro
> 
> > 
> > Dear David
> > 
> > The patch "[TCP]: Set initial_ssthresh default to zero in Cubic and BIC."
> > is not very safe.
> > 
> > With this patch, ftp-transfer stops in my system.
> > (vsftpd-2.0.5-8)
> > 
> > Please revert this patch.
> > 
> > 
> > Best Regards
> > Komuro
> > 
> > >commit 66e1e3b20cbbf99da63e6c1af0fc6d39c2ed099a
> > >Author: David S. Miller <davem@sunset.davemloft.net>
> > >Date:   Wed Jun 13 01:03:53 2007 -0700
> > >
> > >    [TCP]: Set initial_ssthresh default to zero in Cubic and BIC.
> > >    
> > >    Because of the current default of 100, Cubic and BIC perform very
> > >    poorly compared to standard Reno.
> > >    
> > >    In the worst case, this change makes Cubic and BIC as aggressive as
> > >    Reno.  So this change should be very safe.
> > >    
> > >    Signed-off-by: David S. Miller <davem@davemloft.net>
> > >
> > >diff --git a/net/ipv4/tcp_bic.c b/net/ipv4/tcp_bic.c
> > >index 281c9f9..dd9ef65 100644
> > >--- a/net/ipv4/tcp_bic.c
> > >+++ b/net/ipv4/tcp_bic.c
> > >@@ -29,7 +29,7 @@ static int fast_convergence = 1;
> > > static int max_increment = 16;
> > > static int low_window = 14;
> > > static int beta = 819;		/* = 819/1024 (BICTCP_BETA_SCALE) */
> > >-static int initial_ssthresh = 100;
> > >+static int initial_ssthresh;
> > > static int smooth_part = 20;
> > > 
> > > module_param(fast_convergence, int, 0644);
> > >diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
> > >index 1422448..ebfaac2 100644
> > >--- a/net/ipv4/tcp_cubic.c
> > >+++ b/net/ipv4/tcp_cubic.c
> > >@@ -29,7 +29,7 @@
> > > static int fast_convergence __read_mostly = 1;
> > > static int max_increment __read_mostly = 16;
> > > static int beta __read_mostly = 819;	/* = 819/1024 (BICTCP_BETA_SCALE) */
> > >-static int initial_ssthresh __read_mostly = 100;
> > >+static int initial_ssthresh __read_mostly;
> > > static int bic_scale __read_mostly = 41;
> > > static int tcp_friendliness __read_mostly = 1;
> > > 
> 
> 
> -- 
> Komuro <komurojun@nifty.com>


-- 
Komuro <komurojun@nifty.com>

  parent reply	other threads:[~2007-10-14  4:30 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-10-06  4:26 [PATCH] Simplify yenta code Komuro
2007-10-08 17:47 ` Linas Vepstas
2007-10-13 22:36 ` [NOT VERY SAFE] [TCP]: Set initial_ssthresh default to zero in Cubic and BIC Komuro
2007-10-13 22:52   ` David Miller
2007-10-13 22:54     ` David Miller
2007-10-14  1:02   ` Komuro
2007-10-14  2:38     ` David Miller
2007-10-14  4:30       ` Jeff Garzik
2007-10-14  4:28     ` Komuro [this message]
2007-10-14  4:32       ` David Miller
2007-10-14  4:53       ` Komuro
2007-10-14  5:23         ` David Miller
2007-10-15 12:59         ` Komuro
2007-10-15 15:55           ` Stephen Hemminger
2007-10-14 20:34     ` Stephen Hemminger
2008-03-02 12:07   ` [BUG kernel 2.6.25-rc3 IPV6] ping6 -I eth0 ff02::1 causes system hang Komuro
2008-03-04  7:40     ` Andrew Morton
2008-03-08  4:44     ` Komuro
2008-03-08  5:20       ` Komuro
2008-03-08 11:56       ` 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=20071014132851.8d6a9de3.komurojun@nifty.com \
    --to=komurojun@nifty.com \
    --cc=davem@sunset.davemloft.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --subject='Re: [NOT VERY SAFE]     [TCP]: Set initial_ssthresh default to zero in Cubic and BIC.' \
    /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

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).