Re: nr_cpu_ids incorrect on AMD Quad-Core Opteron 8380
From: zhiyi
Date: Tue Feb 02 2010 - 16:34:02 EST
On 2/02/2010, at 8:07 PM, Borislav Petkov wrote:
On Tue, Feb 02, 2010 at 01:49:06PM +1300, zhiyi wrote:
The dmesg relevant to nr_cpu_ids of the quad socket is:
[ 0.000000] NR_CPUS:64 nr_cpumask_bits:64 nr_cpu_ids:32
nr_node_ids:4
No, this is not the relevant info. I was actually looking for the
MADT ACPI
table and whether there are disabled entries like so:
[ 0.000000] ACPI: LAPIC (acpi-id[0x03] lapic-id[0x02] enabled)
[ 0.000000] ACPI: LAPIC (acpi-id[0x04] lapic-id[0x03] enabled)
[ 0.000000] ACPI: LAPIC (acpi-id[0x05] lapic-id[0x84] disabled)
[ 0.000000] ACPI: LAPIC (acpi-id[0x06] lapic-id[0x85] disabled)
because if there are, nr_cpu_ids will include those when you don't
boot
with "possible_cpus=N".
Thanks. I understand the problem now. Below is the related message on
my quad-socket. Not surprisingly nr_cpu_ids should be 32 since the
machine can potentially accommodate 32 cores.
The good thing is that I realized I should use num_present_cpus()
instead of nr_cpu_ids for my purpose (get the number of real cores on
the machine)
Many thanks,
Zhiyi
[ 0.000000] ACPI: LAPIC (acpi_id[0x01] lapic_id[0x00] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x02] lapic_id[0x0c] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x03] lapic_id[0x08] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x04] lapic_id[0x04] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x05] lapic_id[0x01] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x06] lapic_id[0x0d] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x07] lapic_id[0x09] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x08] lapic_id[0x05] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x09] lapic_id[0x02] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x0a] lapic_id[0x0e] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x0b] lapic_id[0x0a] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x0c] lapic_id[0x06] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x0d] lapic_id[0x03] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x0e] lapic_id[0x0f] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x0f] lapic_id[0x0b] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x10] lapic_id[0x07] enabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x11] lapic_id[0x20] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x12] lapic_id[0x21] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x13] lapic_id[0x22] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x14] lapic_id[0x23] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x15] lapic_id[0x24] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x16] lapic_id[0x25] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x17] lapic_id[0x26] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x18] lapic_id[0x27] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x19] lapic_id[0x28] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x1a] lapic_id[0x29] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x1b] lapic_id[0x2a] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x1c] lapic_id[0x2b] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x1d] lapic_id[0x2c] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x1e] lapic_id[0x2d] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x1f] lapic_id[0x2e] disabled)
[ 0.000000] ACPI: LAPIC (acpi_id[0x20] lapic_id[0x2f] disabled)
Anyhow, you can read this for more info: http://www.pubbs.net/kernel/200912/64310/
--
Regards/Gruss,
Boris.
=======================
Zhiyi Huang
Dept of Computer Science
University of Otago
Email: hzy@xxxxxxxxxxxxxx
Phone: 0064-3-4795680
Fax: 0064-3-4798529
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