netdev - Re: e1000 softirq load balancing

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Message-ID: <48F52F43.9040201@cs.utexas.edu>
Date:	Tue, 14 Oct 2008 18:46:11 -0500
From:	Don Porter <porterde@...utexas.edu>
To:	David Miller <davem@...emloft.net>
CC:	linux-net@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: e1000 softirq load balancing

Thanks David.

Would you mind giving me a bit of intuition why I can't have a 1:1 
mapping of CPUs to NICs? 

I am a bit out of my depth here, but I'd like to learn.

Best,
Don

David Miller wrote:
> From: Don Porter <porterde@...utexas.edu>
> Date: Tue, 14 Oct 2008 14:05:34 -0500
>
>   
>> It seems to me that with 4 independent NICs and plenty of CPUs to
>> spare, I ought to be able to assign one softirq daemon to each NIC
>> rather than funnelling all of the traffic through 1 or 2.
>>     
>
> Traffic doesn't get distributed unless the NIC has support
> for RX flow seperation and PCI MSI-X interrupts.  Your NICs
> do not.
>
> So no matter how hard you try, each NIC is going to have it's
> packets processed essentially on one cpu.
>   

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