From: Hagen Paul Pfeifer <hagen@jauu.net>
To: Ivan Novick <novickivan@gmail.com>
Cc: netdev@vger.kernel.org
Subject: Re: 200 millisecond timeouts in TCP
Date: Fri, 4 Jun 2010 01:10:02 +0200 [thread overview]
Message-ID: <20100603231002.GG6914@nuttenaction> (raw)
In-Reply-To: <AANLkTils4KHXwX79cLG6UvVOaDdddMqx-1tyUL3VtLQC@mail.gmail.com>
* Ivan Novick | 2010-06-03 15:37:24 [-0700]:
>Using tcpdump and systemtap I am seeing that sometimes retransmission
>of data is sent after waiting 200 milliseconds. However sometimes
>retransmissions happen quicker.
Quicker as 200ms? Conservatively the minimum TCP RTO should be 1s (rfc2988),
Linux differs from this default and define the minimum RTO to 200ms:
#define TCP_RTO_MIN ((unsigned)(HZ/5))
Can you post the tcpdump traces where the relevant retransmission is recognizable?
>Also do you know if the timeout numbers for TCP are configurable parameters?
Some values are documented in Documentation/networking/ip-sysctl.txt, you can
find the relevant timer implementation in ipv4/tcp_input.c and the definition
of TCP_RTO_MIN in include/net/tcp.h.
Hagen Paul Pfeifer
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Hagen Paul Pfeifer <hagen@jauu.net> || http://jauu.net/
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next prev parent reply other threads:[~2010-06-03 23:10 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-03 22:37 200 millisecond timeouts in TCP Ivan Novick
2010-06-03 22:51 ` Mitchell Erblich
2010-06-03 23:10 ` Hagen Paul Pfeifer [this message]
2010-06-04 0:05 ` Ivan Novick
2010-06-04 0:11 ` Ivan Novick
2010-06-04 0:45 ` Hagen Paul Pfeifer
2010-06-04 1:13 ` Mitchell Erblich
2010-06-04 6:58 ` Ryousei Takano
2010-06-04 15:02 ` Satoru SATOH
2010-06-04 22:55 ` Ryousei Takano
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