[openib-general] Question about interrupt generation

[harish]

Hi All,

I tried the following simple experiment and am not able to understand the
results:

Calcualted the number of interrupts  generated by the infiniband [with
little or no traffic to the NIC] over a period of 10seconds and saw around
10-20 interrupts/sec. Then ran a netperf test and saw around 100+ K
interrupts/sec.  This screwed up my host machine. To reduce the impact of
the interrupts, I add a call back that is scheduled to be periodically
called every few microseconds that masks the irq line used by the NIC and a
little later unmasks the same. Noticed that with no traffic, I see anywhere
between 30-50K interrupts/sec. With the netperf traffic, I see around 120K+
interrupts/sec.

Am a newbie to infiniband technology and so do not understand why so many
interrupts are getting generated when I have my call back periodically
called. Could it be that the Infiniband supports MSI? Or is what I am seeing
IPIs? Or does Infiniband generate interrupts based on types of events and
what I am doing by masking/unmasking the interrupt line is one such event?
Any information/suggestions would be useful.

Thanks in advance,
harish
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