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    Subject[BUG] linux-2.6.28-rc3 regression: IRQ smp_affinities not respected
    Hi all

    One more problem it seems on 2.6.28-rc3

    I wanted to get maximal throughput from my machine on a network bench with 3 Gigabit
    links delivering 600.000 packets per second, so I tried to play with smp_affinity to
    dedicate one CPU for each NIC.

    It worked with 2.6.27, so there is a regression on this part.

    Unfortunatly, git bisect is nearly impossible for me as after two steps
    the resulting kernel doesnt event boot on this machine (same for oprofile
    regression I mentioned earlier)

    # grep eth1 /proc/interrupts
    45: 20425 20418 20445 20441 20345 20349 20384 20397 PCI-MSI-edge eth1
    # cat /proc/irq/45/smp_affinity
    ff
    # echo 1 >/proc/irq/45/smp_affinity
    # cat /proc/irq/45/smp_affinity
    01
    # grep eth1 /proc/interrupts
    45: 20928 20920 20943 20940 20845 20847 20887 20898 PCI-MSI-edge eth1
    # grep eth1 /proc/interrupts
    45: 21037 21030 21053 21049 20953 20956 20997 21007 PCI-MSI-edge eth1
    # grep eth1 /proc/interrupts
    45: 21141 21134 21156 21154 21057 21059 21101 21110 PCI-MSI-edge eth1

    You can see interrupts keep being spreaded on all CPUS instead of CPU0 only.

    That *kills* performance on high end routers and servers.

    07:00.0 Ethernet controller: Broadcom Corporation NetXtreme II BCM5708S Gigabit Ethernet (rev 12)
    Subsystem: Hewlett-Packard Company NC373i Integrated Multifunction Gigabit Server Adapter
    Flags: bus master, 66Mhz, medium devsel, latency 64, IRQ 45
    Memory at fa000000 (64-bit, non-prefetchable) [size=32M]
    [virtual] Expansion ROM at d1000000 [disabled] [size=16K]
    Capabilities: [40] PCI-X non-bridge device.
    Capabilities: [48] Power Management version 2
    Capabilities: [50] Vital Product Data
    Capabilities: [58] Message Signalled Interrupts: 64bit+ Queue=0/0 Enable+

    bnx2 driver

    Thanks


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