netdev - Re: bnx2/BCM5709: why 5 interrupts on a 4 core system (2.6.33.3)

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Message-ID: <4BF04C2F.1050407@ans.pl>
Date:	Sun, 16 May 2010 21:49:03 +0200
From:	Krzysztof Olędzki <ole@....pl>
To:	Michael Chan <mchan@...adcom.com>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: bnx2/BCM5709: why 5 interrupts on a 4 core system (2.6.33.3)

On 2010-05-16 21:24, Krzysztof Olędzki wrote:
> On 2010-05-16 20:51, Michael Chan wrote:
>> Krzysztof Oledzki wrote:
>>
>>>
>>> Why the driver registers 5 interrupts instead of 4? How to
>>> limit it to 4?
>>>
>>
>> The first vector (eth0-0) handles link interrupt and other slow
>> path events.  It also has an RX ring for non-IP packets that are
>> not hashed by the RSS hash.  The majority of the rx packets should
>> be hashed to the rx rings eth0-1 - eth0-4, so I would assign these
>> vectors to different CPUs.
>
> Thank you for your prompt response.
>
> In my case the first vector must be handling something more:
>   - "ping -f 192.168.0.1" increases interrupts on both eth1-0 and eth1-4
>   - "ping -f 192.168.0.2" increases interrupts on both eth1-0 and eth1-3
>   - "ping -f 192.168.0.3" increases interrupts on both eth1-0 and eth1-1
>   - "ping -f 192.168.0.7" increases interrupts on both eth1-0 and eth1-2
>
>              CPU0       CPU1       CPU2       CPU3
>    67:    1563979          0          0          0   PCI-MSI-edge      eth1-0
>    68:    1072869          0          0          0   PCI-MSI-edge      eth1-1
>    69:     137905          0          0          0   PCI-MSI-edge      eth1-2
>    70:     259246          0          0          0   PCI-MSI-edge      eth1-3
>    71:     760252          0          0          0   PCI-MSI-edge      eth1-4
>
> As you can see, eth1-1 + eth1-2 + eth1-3 + eth1-4 ~= eth1-0.
>
> So, it seems that TX or RX is always handled by the first vector.
> I'll try to find if it is TX or RX.
>
> BTW: I'm using .1Q vlans over bonding, does it change anything?

It looks like TX for locally generated packets is always performed on 
eth1-0. I guess it should look differently for forwarded packets?

Best regards,

			Krzysztof Olędzki
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