Re: [PATCH resend] x86,kvm: Add a kernel parameter to disable PV spinlock

[Davidlohr Bueso]

On Mon, 04 Sep 2017, Peter Zijlstra wrote:

> For testing its trivial to hack your kernel and I don't feel this is
> something an Admin can make reasonable decisions about.
>
> So why? In general less knobs is better.

+1.

Also, note how b8fa70b51aa (xen, pvticketlocks: Add xen_nopvspin parameter
to disable xen pv ticketlocks) has no justification as to why its wanted
in the first place. The only thing I could find was from 15a3eac0784
(xen/spinlock: Document the xen_nopvspin parameter):

"Useful for diagnosing issues and comparing benchmarks in over-commit CPU scenarios."

So I vote for no additional knobs, specially for such core code.

Thanks,
Davidlohr