linux-kernel - Re: Packet time delays on multi-core systems

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Message-ID: <20100930123048.GA4094@beaver.vrungel.ru>
Date:	Thu, 30 Sep 2010 16:30:48 +0400
From:	Alexey Vlasov <renton@...ton.name>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	netdev <netdev@...r.kernel.org>
Subject: Re: Packet time delays on multi-core systems

On Wed, Sep 29, 2010 at 11:45:21PM +0200, Eric Dumazet wrote:
> But if you send SYN packets in the same time, (logged), this might
> slow
> down the reception (and answers) of ICMP frames. LOG target can be
> quite
> expensive...

Yes, it's clear that  some slow down can appear, but 100 ms is too much,
and this happens at 200 SYN packets in 2 minutes just as in my example.
On old servers where some tx/rx are missing in NIC card I don't see
such a situation even at more then 1000 SYN-packets per sec.

> Is using other rules gives same problem ?
>
> iptables -A OUTPUT -p tcp -m tcp --dport 80 --tcp-flags

No, only LOG gives such a scheme.

-- 
BRGDS. Alexey Vlasov.
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