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

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Date:	Sun, 16 May 2010 15:33:03 +0200 (CEST)
From:	Krzysztof Oledzki <ole@....pl>
To:	Michael Chan <mchan@...adcom.com>
cc:	netdev@...r.kernel.org
Subject: bnx2/BCM5709: why 5 interrupts on a 4 core system (2.6.33.3)

Hello,

I have a Dell R610 server with BCM5709 NICs. The server has one, 4-core 
CPU (X5570) and four BCM5709 NICs onboard. I would like to assign each 
NIC's interrupt to a different CPU for a better performance. However, as I 
have 5 INTs to assign and only 4 CPUs available, it is not obvious how to 
do it right:

             CPU0       CPU1       CPU2       CPU3
   61:      85085          0          0          0   PCI-MSI-edge      eth1-0
   62:      23046          0          0          0   PCI-MSI-edge      eth1-1
   63:      24525          0          0          0   PCI-MSI-edge      eth1-2
   64:      77801          0          0          0   PCI-MSI-edge      eth1-3
   65:      24006          0          0          0   PCI-MSI-edge      eth1-4

# uname -r
2.6.33.3

# dmesg |grep  0000:01:00.0
bnx2 0000:01:00.0: PCI INT A -> GSI 36 (level, low) -> IRQ 36
bnx2 0000:01:00.0: setting latency timer to 64
bnx2 0000:01:00.0: firmware: requesting bnx2/bnx2-mips-09-5.0.0.j3.fw
bnx2 0000:01:00.0: firmware: requesting bnx2/bnx2-rv2p-09-5.0.0.j3.fw
bnx2 0000:01:00.0: irq 61 for MSI/MSI-X
bnx2 0000:01:00.0: irq 62 for MSI/MSI-X
bnx2 0000:01:00.0: irq 63 for MSI/MSI-X
bnx2 0000:01:00.0: irq 64 for MSI/MSI-X
bnx2 0000:01:00.0: irq 65 for MSI/MSI-X
bnx2 0000:01:00.0: irq 66 for MSI/MSI-X
bnx2 0000:01:00.0: irq 67 for MSI/MSI-X
bnx2 0000:01:00.0: irq 68 for MSI/MSI-X
bnx2 0000:01:00.0: irq 69 for MSI/MSI-X

Why the driver registers 5 interrupts instead of 4? How to limit it to 4?

Best regards,

 				Krzysztof Olędzki