linux-kernel - Re: poll() blocked / packets not received ?

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Message-ID: <48FC7BEE.1020701@motion-twin.com>
Date:	Mon, 20 Oct 2008 14:39:10 +0200
From:	Nicolas Cannasse <ncannasse@...ion-twin.com>
To:	swivel@...lls.gnugeneration.com
CC:	linux-kernel@...r.kernel.org
Subject: Re: poll() blocked / packets not received ?

> TCP being reliable can block indefinitely, you can employ TCP keepalive
> to change indefinite to quite a long time.

Ok, funny thing is that we just found what is occurring...

We had a process that was on a regular basis doing the following :

conntrack -F

This was done in order to prevent the table to grow too big, because we 
were reaching the maximum size as told by :

/proc/sys/net/ipv4/netfilter/ip_conntrack_max
   and
/proc/sys/net/ipv4/netfilter/ip_conntrack_count

Seems like when there are active connections, this will break netfilter 
and stop delivering packets to the socket.

At least I will have nice sleep tonight.

Best,
Nicolas
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