netdev - Re: Network card IRQ balancing with Intel 5000 series chipsets

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Message-ID: <Pine.LNX.4.64.0612290255501.12445@bizon.gios.gov.pl>
Date:	Fri, 29 Dec 2006 03:04:06 +0100 (CET)
From:	Krzysztof Oledzki <olel@....pl>
To:	jamal <hadi@...erus.ca>
cc:	Robert Iakobashvili <coroberti@...il.com>,
	Arjan van de Ven <arjan@...radead.org>,
	netdev@...r.kernel.org
Subject: Re: Network card IRQ balancing with Intel 5000 series chipsets



On Wed, 27 Dec 2006, jamal wrote:

> On Wed, 2006-27-12 at 09:09 +0200, Robert Iakobashvili wrote:
>
>>
>> My scenario is treatment of RTP packets in kernel space with a single network
>> card (both Rx and Tx). The default of the Intel 5000 series chipset is
>> affinity of each
>> network card to a certain CPU. Currently, neither with irqbalance nor
>> with kernel
>> irq-balancing (MSI and io-apic attempted) I do not find a way to
>> balance that irq.
>
> In the near future, when the NIC vendors wake up[1] because CPU vendors
> - including big bad Intel -  are going to be putting out a large number
> of hardware threads, you should be able to do more clever things with
> such a setup. At the moment, just tie it to a single CPU and have your
> other processes that are related running/bound on the other cores so you
> can utilize them. OTOH, you say you are only using 30% of the one CPU,
> so it may not be a big deal to tie your single nic to on cpu.

Anyway, it seems that with more advanced firewalls/routers kernel spends 
most of a time in IPSec/crypto code, netfilter conntrack and iptables 
rules/extensions, routing lookups, etc and not in hardware IRQ handler. 
So, it would be nice if this part coulde done by all CPUs.

Best regards,


 			Krzysztof Olędzki