diff options
| author | Josh Boyer <jwboyer@redhat.com> | 2013-11-05 09:37:29 -0500 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-11-06 08:16:28 +0100 |
| commit | bb61ccc7dbcbc1ed4600bef5610d99ec91fd7032 (patch) | |
| tree | dc8bb73aef418d05bfea274053e7887048c39200 /arch/x86/Kconfig | |
| parent | a477c8594bee3bff639739c48258a8c737ab721e (diff) | |
| download | lwn-bb61ccc7dbcbc1ed4600bef5610d99ec91fd7032.tar.gz lwn-bb61ccc7dbcbc1ed4600bef5610d99ec91fd7032.zip | |
x86/cpu: Allow higher NR_CPUS values
The current range for SMP configs is 2 - 512 CPUs, or a full
4096 in the case of MAXSMP. There are machines that have 1024
CPUs in them today and configuring a kernel for that means you
are forced to set MAXSMP. This adds additional unnecessary
overhead. While that overhead might be considered tiny for
large machines, it isn't necessarily so if you are building a
kernel that runs across a wide variety of machines.
To cover the range of more common machines today, we allow
NR_CPUS to be up to 4096 when CPUMASK_OFFSTACK is enabled.
Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Cc: prarit@redhat.com
Cc: Russ Anderson <rja@sgi.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20131105143728.GJ9944@hansolo.jdub.homelinux.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/Kconfig')
| -rw-r--r-- | arch/x86/Kconfig | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f67e839f06c8..f03e428112eb 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -825,14 +825,16 @@ config MAXSMP config NR_CPUS int "Maximum number of CPUs" if SMP && !MAXSMP range 2 8 if SMP && X86_32 && !X86_BIGSMP - range 2 512 if SMP && !MAXSMP + range 2 512 if SMP && !MAXSMP && !CPUMASK_OFFSTACK + range 2 4096 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64 default "1" if !SMP default "4096" if MAXSMP default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000) default "8" if SMP ---help--- This allows you to specify the maximum number of CPUs which this - kernel will support. The maximum supported value is 512 and the + kernel will support. If CPUMASK_OFFSTACK is enabled, the maximum + supported value is 4096, otherwise the maximum value is 512. The minimum value which makes sense is 2. This is purely to save memory - each supported CPU adds |