So I've read the excellent "Beyond Softnet" paper about
how SMP is inherently likely to re-order packet flows,
and I'm trying to use the work around where I assign
IRQs to CPUs, in this case for a gigabit network
I have dual PIIIs 1GHz on serverworks chipsets. I'm using the
DGE550 66MHz/64bit GigE cards over copper. Each system has
1.5Gbytes of RAM. Each kernel is 2.4.19-pre5aa1 and /dev/epoll.
To force IRQ affinity to CPU 2 or 2, I type the following:
echo 2 > /proc/irq/23/smp_affinity
when I send traffic to this interface I only see
IRQs on the second CPU on /proc/interrupts. All
is good so far.
However, a network device I'm testing between my hosts
keeps seeing re-ordered TCP sessions. When I reboot and
specify maxcpus=1 and re-run the test I get none.
Am I doing something really wrong here or does this
workaround no longer work ?
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