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[IA64] Count disabled cpus as potential hot-pluggable CPUs

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Minor updates to earlier patch.
- Added to documentation to add ia64 as well.
- Minor clarification on how to use disabled cpus
- used plain max instead of max_t per Andew Morton.

Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
This commit is contained in:
Ashok Raj 2006-02-16 14:01:48 -08:00 committed by Tony Luck
parent 6f6d75825d
commit 8f8b1138fc
2 changed files with 20 additions and 13 deletions
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14
Documentation/cpu-hotplug.txt
View File

@ -44,10 +44,20 @@ maxcpus=n Restrict boot time cpus to n. Say if you have 4 cpus, using
maxcpus=2 will only boot 2. You can choose to bring the maxcpus=2 will only boot 2. You can choose to bring the
other cpus later online, read FAQ's for more info. other cpus later online, read FAQ's for more info.
additional_cpus=n [x86_64 only] use this to limit hotpluggable cpus. additional_cpus*=n Use this to limit hotpluggable cpus. This option sets
This option sets
cpu_possible_map = cpu_present_map + additional_cpus cpu_possible_map = cpu_present_map + additional_cpus
(*) Option valid only for following architectures
- x86_64, ia64
ia64 and x86_64 use the number of disabled local apics in ACPI tables MADT
to determine the number of potentially hot-pluggable cpus. The implementation
should only rely on this to count the #of cpus, but *MUST* not rely on the
apicid values in those tables for disabled apics. In the event BIOS doesnt
mark such hot-pluggable cpus as disabled entries, one could use this
parameter "additional_cpus=x" to represent those cpus in the cpu_possible_map.
CPU maps and such CPU maps and such
----------------- -----------------
[More on cpumaps and primitive to manipulate, please check [More on cpumaps and primitive to manipulate, please check

19
arch/ia64/kernel/acpi.c
View File

@ -794,24 +794,21 @@ __init void prefill_possible_map(void)
int possible, disabled_cpus; int possible, disabled_cpus;
disabled_cpus = total_cpus - available_cpus; disabled_cpus = total_cpus - available_cpus;
if (additional_cpus == -1) { if (additional_cpus == -1) {
if (disabled_cpus > 0) { if (disabled_cpus > 0)
possible = total_cpus;
additional_cpus = disabled_cpus; additional_cpus = disabled_cpus;
} else
else {
possible = available_cpus;
additional_cpus = 0; additional_cpus = 0;
} }
} else {
possible = available_cpus + additional_cpus; possible = available_cpus + additional_cpus;
}
if (possible > NR_CPUS) if (possible > NR_CPUS)
possible = NR_CPUS; possible = NR_CPUS;
printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n", printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
possible, possible, max((possible - available_cpus), 0));
max_t(int, additional_cpus, 0));
for (i = 0; i < possible; i++) for (i = 0; i < possible; i++)
cpu_set(i, cpu_possible_map); cpu_set(i, cpu_possible_map);