Messages in this thread | | | Date | Thu, 24 Jan 2013 13:22:23 +0100 | From | Leandro Lucarella <> | Subject | Re: Doubts about listen backlog and tcp_max_syn_backlog |
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On Wed, Jan 23, 2013 at 11:28:08AM -0800, Rick Jones wrote: > >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.
I was just kind of quoting the name given by netstat: "SYNs to LISTEN sockets dropped" (for kernel 3.0, I noticed newer kernels don't have this stat anymore, or the name was changed). I still don't know if we are talking about the same thing.
> 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.
So the only reason to experience these high times spent in connect() should be because a SYN or SYN|ACK was actually loss in a lower layer, like an error in the network device or a transmission error?
> That would be 3 (,9, 21, etc...) seconds on a kernel with 3 > seconds as the initial retransmission timeout.
Which can't be changed without recompiling, right?
Thanks!
-- Leandro Lucarella sociomantic labs GmbH http://www.sociomantic.com
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