Re: [PATCH] Avoid mask based num_possible_cpus and num_online_cpus -v5

[Rusty Russell]

On Mon, 13 Feb 2012 13:57:45 -0800, Tony Luck <tony.luck@xxxxxxxxx> wrote:
> On Mon, Feb 13, 2012 at 12:44 PM, Srivatsa S. Bhat
> <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> wrote:
> > IOW, what output do you see from the following printk from
> > arch/ia64/kernel/smpboot.c?
> >
> > printk(KERN_INFO "Total of %d processors activated (%lu.%02lu BogoMIPS).\n",
> > Â Â Â Â (int)num_online_cpus(), bogosum/(500000/HZ), (bogosum/(5000/HZ))%100);
> 
> That is a complicated question - because linux-next also has patches
> by Arjan that
> change how (when) cpus are brought online. Initially I blamed his
> patches and tried
> reverting them ... and saw the symptom you are wondering about (message said
> "Total of 1 processors", but the BogoMIPs was a number big enough to be all of
> them. Thanks to you, I can now understand why.
> 
> Fix will be to stop ia64 from messing directly with cpu_online_map?

Yes, and the other architectures.

We're well within reach of removing cpu_*_map now I think.

Cheers,
Rusty.

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