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authorJan Beulich <JBeulich@novell.com>2010-05-24 12:13:17 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2010-05-24 13:31:52 -0700
commit5f2eb55026c91f8400ab4469aff88b2e201b5616 (patch)
tree1cef5c2d26e0b38f3f9f61f103d6de840f7f2061 /arch
parentb46fc5f235be04a7f77fb2af1d8cb809889c25c1 (diff)
downloadop-kernel-dev-5f2eb55026c91f8400ab4469aff88b2e201b5616.zip
op-kernel-dev-5f2eb55026c91f8400ab4469aff88b2e201b5616.tar.gz
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')
-rw-r--r--arch/x86/kernel/smpboot.c26
1 files changed, 23 insertions, 3 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 763d815..37462f1 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;
}
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