Public bug reported:
Binary package hint: irqbalance
irqbalance-0.55-2 seems to misconfigure my Linux box. I have a Sun
4100M2 (2xdual core AMD Opteron 2216) running Ubuntu Hardy (64 bit). I
have been benchmarking software that performs lots of network I/O, using
8 network cards on the box (6xe1000 2xforcedeth)
With irqbalance running as a daemon, when the benchmark is under way,
there are always two ksoftirqd processes running, each consuming 100%
CPU. This unsurprisingly causes a massive slowdown in the benchmark. I
can achieve about 4GBits of traffic in total.
I've found two ways of fixing the problem:
1) Kill irqbalance completely before the benchmark runs, OR run irqbalance at
bootup with its --oneshot option.
2) Downgrade to irqbalance-0.12-2 from Debian. This version chosen simply
because I have used this same machine with a pure Debian installation in the
past, and that was the irqbalance on there.
With either of these two steps, throughput rises to about 8GBits and
there are no ksoftirqd processes eating CPU. Solution 2 gives slightly
better performance, presumably because irqbalance is able to move IRQs
around as needed. I would prefer to have an irqbalance running, because
while the benchmark has regular network traffic on all NICs, in 'real
world' use this machine could have unpredictable network traffic and the
initial IRQ allocations may not be optimal.
Running on kernel linux-image-2.6.24-amd64-generic (various versions
have failed to make a difference to the behaviour, so I suspect the
problem is irqbalance-specific rather than kernel-specific)
** Affects: irqbalance (Ubuntu)
Importance: Undecided
Status: New
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irqbalance causes ksoftirqd to use 100% CPU
https://bugs.launchpad.net/bugs/297121
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