From: Rick Jones <rick.jones2@hp.com>
To: Ben Greear <greearb@candelatech.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>,
netdev <netdev@vger.kernel.org>
Subject: Re: TCP funny-ness when over-driving a 1Gbps link.
Date: Thu, 19 May 2011 17:24:39 -0700 [thread overview]
Message-ID: <1305851079.8149.1127.camel@tardy> (raw)
In-Reply-To: <4DD5B202.7080701@candelatech.com>
> >> [root@i7-965-1 igb]# netstat -an|grep tcp|grep 8.1.1
> >> tcp 0 0 8.1.1.1:33038 0.0.0.0:* LISTEN
> >> tcp 0 0 8.1.1.1:33040 0.0.0.0:* LISTEN
> >> tcp 0 0 8.1.1.1:33042 0.0.0.0:* LISTEN
> >> tcp 0 9328612 8.1.1.2:33039 8.1.1.1:33040 ESTABLISHED
> >> tcp 0 17083176 8.1.1.1:33038 8.1.1.2:33037 ESTABLISHED
> >> tcp 0 9437340 8.1.1.2:33037 8.1.1.1:33038 ESTABLISHED
> >> tcp 0 17024620 8.1.1.1:33040 8.1.1.2:33039 ESTABLISHED
> >> tcp 0 19557040 8.1.1.1:33042 8.1.1.2:33041 ESTABLISHED
> >> tcp 0 9416600 8.1.1.2:33041 8.1.1.1:33042 ESTABLISHED
> >
> > I take it your system has higher values for the tcp_wmem value:
> >
> > net.ipv4.tcp_wmem = 4096 16384 4194304
>
> Yes:
> [root@i7-965-1 igb]# cat /proc/sys/net/ipv4/tcp_wmem
> 4096 16384 50000000
Why?!? Are you trying to get link-rate to Mars or something? (I assume
tcp_rmem is similarly set...) If you are indeed doing one 1 GbE, and no
more than 100ms then the default (?) of 4194304 should have been more
than sufficient.
> > and whatever is creating the TCP connections is not making explicit
> > setsockopt() calls to set SO_*BUF.
>
> It is configured not to, but if you know of an independent way to verify
> that, I'm interested.
You could always strace the code.
rick
next prev parent reply other threads:[~2011-05-20 0:24 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-19 22:47 TCP funny-ness when over-driving a 1Gbps link Ben Greear
2011-05-19 23:18 ` Stephen Hemminger
2011-05-19 23:20 ` Ben Greear
2011-05-19 23:42 ` Ben Greear
2011-05-20 0:05 ` Rick Jones
2011-05-20 0:12 ` Ben Greear
2011-05-20 0:24 ` Rick Jones [this message]
2011-05-20 0:37 ` Ben Greear
2011-05-20 0:46 ` Rick Jones
2011-05-20 3:39 ` Ben Greear
2011-05-20 21:33 ` TCP funny-ness when over-driving a 1Gbps link (and wifi) Ben Greear
2011-05-26 15:28 ` Chris Friesen
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