irqbalancer subset policy and CPU lock up on storage controller.

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> > What should be the solution if we really want to slow down IO
> > submission to avoid CPU lockup. We don't want only one CPU to keep
> > busy for completion.
> >
> > Any suggestion ?
> >
> Yup, file a bug with Oracle :)

Neil -

Thanks for info. I understood to use latest <irqbalance>...that was
already attempted. I tried with latest irqbalance and I see expected
behavior as long as I provide <exact> or <subset> + <--poliicyscript>.
We are planning for the same, but wanted to understand what is latest
<irqbalancer> default settings. Is there any reason we are seeing default
settings changed from  subset to ignore ?

> What you're seeing looks like at least in part a bug with your (very
> version of irqbalance.  I seem to recall fixing more than a few bugs
> with affinity masks from the hint files and banned_cpu options.  I
> suggest that you test with an upstream version of irqbalance and contact
> oracle to update their version to something more recent.

I see CPU lock up issue does not go if <rq_affinity> is set to 1 in
storage stack and if <irqbalance> policy set to <ignore>.   With <ignore>
policy, I see  only limited logic cpu of local NUMA node is busy doing
completion. We are still seeing may IO pumping from remote NUMA node. This
will cause CPU lockup as <rq_affinity> does not migrate softirq to _exact_
submitter.  Not sure what majority of h/w require from <irqbalanace> ? Is
it <ignore> kind of policy good choice or <subset> ?

` Kashyap

> Regards
> Neil
> > ` Kashyap
> >
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> > irqbalance at
> >
> >

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