diff options
| author | Jan Beulich <JBeulich@novell.com> | 2010-05-24 12:13:17 -0700 |
|---|---|---|
| committer | H. Peter Anvin <hpa@linux.intel.com> | 2010-05-24 13:31:52 -0700 |
| commit | 5f2eb55026c91f8400ab4469aff88b2e201b5616 (patch) | |
| tree | 1cef5c2d26e0b38f3f9f61f103d6de840f7f2061 /arch/x86/kernel/smpboot.c | |
| parent | b46fc5f235be04a7f77fb2af1d8cb809889c25c1 (diff) | |
x86: "nosmp" command line option should force the system into UP mode
Bits set in cpu_possible_mask prior to the execution of
prefill_possible_map() (i.e. when parsing ACPI or MPS tables) would
prevent the SMP alternatives logic from switching to UP mode, plus
unnecessary setup of per-CPU data for CPUs that can never come online.
Additionally, without CONFIG_HOTPLUG_CPU disabled CPUs can never come
online, and hence setting cpu_possible_mask bits for them is again a
simple waste of resources.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
LKML-Reference: <201005241913.o4OJDH3Z010874@imap1.linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/smpboot.c')
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 26 |
1 files changed, 23 insertions, 3 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 763d815e27a..37462f1ddba 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -1215,9 +1215,17 @@ __init void prefill_possible_map(void) if (!num_processors) num_processors = 1; - if (setup_possible_cpus == -1) - possible = num_processors + disabled_cpus; - else + i = setup_max_cpus ?: 1; + if (setup_possible_cpus == -1) { + possible = num_processors; +#ifdef CONFIG_HOTPLUG_CPU + if (setup_max_cpus) + possible += disabled_cpus; +#else + if (possible > i) + possible = i; +#endif + } else possible = setup_possible_cpus; total_cpus = max_t(int, possible, num_processors + disabled_cpus); @@ -1230,11 +1238,23 @@ __init void prefill_possible_map(void) possible = nr_cpu_ids; } +#ifdef CONFIG_HOTPLUG_CPU + if (!setup_max_cpus) +#endif + if (possible > i) { + printk(KERN_WARNING + "%d Processors exceeds max_cpus limit of %u\n", + possible, setup_max_cpus); + possible = i; + } + printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n", possible, max_t(int, possible - num_processors, 0)); for (i = 0; i < possible; i++) set_cpu_possible(i, true); + for (; i < NR_CPUS; i++) + set_cpu_possible(i, false); nr_cpu_ids = possible; } |