Re: disabled APICs being counted as processors ?

From: Ingo Molnar
Date: Sat Jan 25 2014 - 02:41:43 EST



* Dave Jones <davej@xxxxxxxxxx> wrote:

> I have a system with 4 cores (configured with CONFIG_NR_CPUS=4) that shows during boot..
>
> [ 0.000000] smpboot: 8 Processors exceeds NR_CPUS limit of 4
>
> it looks like this is because..
>
> [ 0.000000] ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled)
> [ 0.000000] ACPI: LAPIC (acpi_id[0x02] lapic_id[0x02] enabled)
> [ 0.000000] ACPI: LAPIC (acpi_id[0x03] lapic_id[0x04] enabled)
> [ 0.000000] ACPI: LAPIC (acpi_id[0x04] lapic_id[0x06] enabled)
> [ 0.000000] ACPI: LAPIC (acpi_id[0x05] lapic_id[0xff] disabled)
> [ 0.000000] ACPI: LAPIC (acpi_id[0x06] lapic_id[0xff] disabled)
> [ 0.000000] ACPI: LAPIC (acpi_id[0x07] lapic_id[0xff] disabled)
> [ 0.000000] ACPI: LAPIC (acpi_id[0x08] lapic_id[0xff] disabled)
>
> Should the CPU counting code be ignoring those disabled APICs ?

Hm, so to the kernel it looks like as if those were 'possible CPUs',
in theory hotpluggable. Not sure what they are - disabled cores in an
8-core system? Or BIOS reporting crap?

But perhaps the boot message could be improved to say something like:

> [ 0.000000] smpboot: 8 possible processors exceeds NR_CPUS limit of 4

?

Thanks,

Ingo
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