Re: [PATCH -v2 5/5] x86: use dmi check to treat disabled cpus ashotplug cpus.

From: Yinghai Lu
Date: Tue Jan 12 2010 - 20:57:09 EST

On 01/12/2010 05:48 PM, Suresh Siddha wrote:
> On Tue, 2010-01-12 at 16:05 -0800, Yinghai Lu wrote:
>> On 01/12/2010 03:56 PM, Suresh Siddha wrote:
>>> On Tue, 2010-01-12 at 15:17 -0800, Yinghai Lu wrote:
>>>> some systems that have disable cpus entries because same
>>>> BIOS will support 2 sockets and 4 sockets and more at
>>>> same time, BIOS just leave some disable entries, but
>>>> those system do not support cpu hotplug. we don't need
>>>> treat disabled_cpus as hotplug cpus.
>>>> so we can make nr_cpu_ids smaller and save more space
>>>> (pcpu data allocations), and could make some systems run
>>>> with logical flat instead of physical flat apic mode
>>>> -v2: change to black list instead
>>> I don't think this list will work because every HT system with HT
>>> disabled in the bios shows that logical cpu as disabled.
>> so you want to treat those disabled cpus in the those system as hotplug cpus or not?
> They are really not hot plug cpus, so they can also take advantage of
> what you are trying to provide with this patch.

you mean this blacklist could be too long?

switch to whitelist for the box can treat disabled cpus as hotplug cpus?

> Also I am very confused with what exactly you are doing with the dmi
> list..
> + printk(KERN_NOTICE "%s detected: treat disabled cpus as hotplug ones\n", d->ident);
> + treat_disabled_cpus_as_hotplug = 0;
sorry, forget to change the print out.

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