Messages in this thread Patch in this message | | | Date | Thu, 16 Feb 2006 08:20:25 +0100 | From | Heiko Carstens <> | Subject | [patch 4/4] s390: possible_cpus parameter |
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From: Heiko Carstens <heiko.carstens@de.ibm.com>
Introduce possible_cpus command line option. Hard sets the number of bits set in cpu_possible_map. Unlike the additional_cpus parameter this one guarantees that num_possible_cpus() will stay constant even if the system gets rebooted and a different number of cpus are present at startup.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> ---
Documentation/cpu-hotplug.txt | 6 ++++++ arch/s390/kernel/smp.c | 14 +++++++++++--- 2 files changed, 17 insertions(+), 3 deletions(-)
diff -purN a/Documentation/cpu-hotplug.txt b/Documentation/cpu-hotplug.txt --- a/Documentation/cpu-hotplug.txt 2006-02-16 07:56:45.000000000 +0100 +++ b/Documentation/cpu-hotplug.txt 2006-02-16 08:00:39.000000000 +0100 @@ -50,6 +50,12 @@ additional_cpus=n [x86_64, s390 only] us This option sets cpu_possible_map = cpu_present_map + additional_cpus +possible_cpus=n [s390 only] use this to set hotpluggable cpus. + This option sets possible_cpus bits in + cpu_possible_map. Thus keeping the numbers of bits set + constant even if the machine gets rebooted. + This option overrides additional_cpus. + CPU maps and such ----------------- [More on cpumaps and primitive to manipulate, please check diff -purN a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c --- a/arch/s390/kernel/smp.c 2006-02-16 07:56:45.000000000 +0100 +++ b/arch/s390/kernel/smp.c 2006-02-16 07:56:35.000000000 +0100 @@ -673,15 +673,16 @@ __cpu_up(unsigned int cpu) } static unsigned int __initdata additional_cpus; +static unsigned int __initdata possible_cpus; void __init smp_setup_cpu_possible_map(void) { unsigned int pcpus, cpu; - pcpus = smp_count_cpus() + additional_cpus; + pcpus = min(smp_count_cpus() + additional_cpus, (unsigned int) NR_CPUS); - if (pcpus > NR_CPUS) - pcpus = NR_CPUS; + if (possible_cpus) + pcpus = min(possible_cpus, (unsigned int) NR_CPUS); for (cpu = 0; cpu < pcpus; cpu++) cpu_set(cpu, cpu_possible_map); @@ -698,6 +699,13 @@ static int __init setup_additional_cpus( } early_param("additional_cpus", setup_additional_cpus); +static int __init setup_possible_cpus(char *s) +{ + possible_cpus = simple_strtoul(s, NULL, 0); + return 0; +} +early_param("possible_cpus", setup_possible_cpus); + int __cpu_disable(void) { - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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