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s390/smp: limit number of cpus in possible cpu mask

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Limit the number of bits to the maximum number of cpus a machine
can have.
possible_cpu_mask typically will have more bits set than a machine
may physically have. This results in wasted memory during per-cpu
memory allocations, if the possible mask contains more cpus than
physically possible for a given configuration.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens
2014-03-10 14:50:16 +01:00
committed by Martin Schwidefsky
parent 36a554021b
commit cf813db0b4
3 changed files with 26 additions and 6 deletions
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8
arch/s390/kernel/smp.c
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@@ -773,11 +773,11 @@ void __noreturn cpu_die(void)
void __init smp_fill_possible_mask(void)
{
unsigned int possible, cpu;
unsigned int possible, sclp, cpu;
possible = setup_possible_cpus;
if (!possible)
possible = MACHINE_IS_VM ? 64 : nr_cpu_ids;
sclp = sclp_get_max_cpu() ?: nr_cpu_ids;
possible = setup_possible_cpus ?: nr_cpu_ids;
possible = min(possible, sclp);
for (cpu = 0; cpu < possible && cpu < nr_cpu_ids; cpu++)
set_cpu_possible(cpu, true);
}