Re: [PATCH 2/2] x86: implement multiple queues for smp function call IPIs

From: Andi Kleen
Date: Fri Aug 01 2008 - 10:17:43 EST


> So ... how about my original suggestion, to add a (default-off) boot
> option that reduces the queues to 1? I.e. lets have something in place
> from day 1 on that could be quirk-handler-driven, should the need arise.
> "apic=simpleipi" or something like that.
>
> In a year or two, once this all has proven itself fine on a broad range
> of systems, we'll laugh out loud at being so cautious and can remove the
> boot option for good ;-)

I agree that adding a boot option to turn it off is a good idea (assuming
it doesn't take too much code to implement) Adding such paranoid boot options early
has saved my ass a few times in the past.

Only tricky bit is use if () not "modulo variable", because the if ()
will be much faster than a division through an arbitary number.

-Andi
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