smp affinity makes a difference

2016-07-13

A good driver.

Having a driver that uses the proper interrupt handling makes a difference in high bandwidth pci devices like RAID cards and Infiniband.

For example having the stock 2.6.32-220 megasas driver only makes use of one interrupt.

This was the stock driver in the centos 2.6.32-220 kernel

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[[email protected] mnt]# cat /proc/interrupts |grep megasas
79: 2506 0 0 0 0 0 0 0 IR-PCI-MSI-edge megasas

This is the driver from LSI compiled against the same kernel sources. Notice the additional interrupt usage.

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[[email protected] mnt]# cat /proc/interrupts |grep megasas
80: 2506 0 0 0 0 0 0 0 IR-PCI-MSI-edge megasas
81: 124 0 0 0 0 0 0 0 IR-PCI-MSI-edge megasas
82: 24 0 0 0 0 0 0 0 IR-PCI-MSI-edge megasas
83: 7 0 0 0 0 0 0 0 IR-PCI-MSI-edge megasas
84: 993 0 0 0 0 0 0 0 IR-PCI-MSI-edge megasas
85: 80 0 0 0 0 0 0 0 IR-PCI-MSI-edge megasas
86: 17 0 0 0 0 0 0 0 IR-PCI-MSI-edge megasas
87: 8 0 0 0 0 0 0 0 IR-PCI-MSI-edge megasas

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