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Date:      Thu, 24 Apr 2008 01:03:57 +0100 (BST)
From:      Mark Hills <mark@pogo.org.uk>
To:        Andre Oppermann <andre@freebsd.org>
Cc:        Peter Jeremy <peterjeremy@optushome.com.au>, freebsd-net@freebsd.org
Subject:   Re: read() returns ETIMEDOUT on steady TCP connection
Message-ID:  <alpine.BSO.1.10.0804240030500.6125@zrgural.vwaro.pbz>
In-Reply-To: <480E7901.5000804@freebsd.org>
References:  <alpine.BSO.1.10.0804191437400.21362@zrgural.vwaro.pbz> <20080420025010.GJ73016@server.vk2pj.dyndns.org> <alpine.BSO.1.10.0804201238480.31900@zrgural.vwaro.pbz> <480BBD7E.8010700@freebsd.org> <alpine.BSO.1.10.0804210740100.1745@zrgural.vwaro.pbz> <480C9AC6.8090802@freebsd.org> <480E7901.5000804@freebsd.org>

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On Wed, 23 Apr 2008, Andre Oppermann wrote:

> http://people.freebsd.org/~andre/tcp_output-error-log.diff
>
> Please apply this patch and enable the sysctl net.inet.tcp.log_debug=1
> and report any output.  You likely get some (normal) noise from syncache.
> What we are looking for is reports from tcp_output.

Hi Andre, I've applied the patch and tested.

Aside from syncache noise, I get a constant stream of 'error 55' 
(ENOBUFS?), once the number of connection gets to around 150 at 192kbps.

TCP: [192.168.5.43]:52153 to [192.168.5.40]:8080; tcp_output: error 55 while sending

192.168.5.40 is the IP address of this host, running the server.

I tried to correlate the point of the application receiving ETIMEDOUT with 
these messages, but that is tricky as it seems to be outputting a lot of 
messages, and multiple messages over eachother (see below).

Because of the mention of no buffer space available, I checked the values 
of net.inet.tcp.sendbuf* and recvbuf*, and increased the max values with 
no effect.

When I get time I will modify the kernel to print errors which aren't 
ENOBUFS to see if there are any others. But in the meantime, this sounds 
like a problem to me. Is that correct?

Mark


:8080; tcp_output: error 55 while sending
TCP: [192.168.5.42]:57384T CtPo:  [[119922..116688..55..4402]]::85048400;1  ttoc p[_1o9u2t.p1u6t8:. 5e.r4r0o]r: 8080;5 5t cwp_hoiultep uste:n deirnrgor 55 while sending
TCP: [192.168.5.42]:57382 to [192.168.5.40]:8080; tcp_output: error 55 while sending
TCP: [192.168.5.42]:57381 to [192.168.5.40]:8080; tcp_output: error 55 while sending
TCP: [192.168.5.42]:57380 to [192.168.5.40]:8080; tcp_output: error 55 while sending




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