From: Rick Jones <rick.jones2@hp.com>
To: Leandro Lucarella <leandro.lucarella@sociomantic.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: Doubts about listen backlog and tcp_max_syn_backlog
Date: Wed, 23 Jan 2013 11:28:08 -0800 [thread overview]
Message-ID: <510039C8.7040401@hp.com> (raw)
In-Reply-To: <20130123104736.GK4608@sociomantic.com>
On 01/23/2013 02:47 AM, Leandro Lucarella wrote:
> Thanks for the info. I'm definitely dropping SYNs and sending cookies,
> around 50/s. Is there any way to tell how many connections are queued in
> a particular socket?
I am not familiar with one. Doesn't mean there isn't one, only that I
am not able to think of it.
> Then if syncookies are enabled, the time spent in connect() shouldn't be
> bigger than 3 seconds even if SYNs are being "dropped" by listen, right?
Do you mean if "ESTABLISHED" connections are dropped because the listen
queue is full? I don't think I would put that as "SYNs being dropped by
listen" - too easy to confuse that with an actual dropping of a SYN segment.
But yes, I would not expect a connect() call to remain incomplete for
any longer than it took to receive an SYN|ACK from the other end. That
would be 3 (,9, 21, etc...) seconds on a kernel with 3 seconds as the
initial retransmission timeout.
rick
next prev parent reply other threads:[~2013-01-23 19:28 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-22 16:10 Doubts about listen backlog and tcp_max_syn_backlog Leandro Lucarella
2013-01-22 16:45 ` Eric Dumazet
2013-01-22 16:59 ` Leandro Lucarella
2013-01-22 17:13 ` Eric Dumazet
2013-01-22 18:17 ` Rick Jones
2013-01-22 18:42 ` Leandro Lucarella
2013-01-22 22:01 ` Rick Jones
2013-01-23 10:47 ` Leandro Lucarella
2013-01-23 19:28 ` Rick Jones [this message]
2013-01-24 12:22 ` Leandro Lucarella
2013-01-24 18:44 ` Rick Jones
2013-01-24 19:21 ` Leandro Lucarella
2013-01-25 6:12 ` Nivedita SInghvi
2013-01-25 10:05 ` Leandro Lucarella
2013-01-28 2:48 ` Nivedita Singhvi
2013-01-28 5:21 ` Vijay Subramanian
2013-01-28 14:40 ` Leandro Lucarella
2013-01-28 13:08 ` Leandro Lucarella
2013-01-28 2:49 ` Nivedita Singhvi
2013-01-23 20:48 ` Vijay Subramanian
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