Messages in this thread Patch in this message | | | Date | Sun, 14 Oct 2007 10:02:45 +0900 | From | Komuro <> | Subject | Re: [NOT VERY SAFE] [TCP]: Set initial_ssthresh default to zero in Cubic and BIC. |
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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> - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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