From bb61ccc7dbcbc1ed4600bef5610d99ec91fd7032 Mon Sep 17 00:00:00 2001 From: Josh Boyer Date: Tue, 5 Nov 2013 09:37:29 -0500 Subject: 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 Cc: prarit@redhat.com Cc: Russ Anderson Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/20131105143728.GJ9944@hansolo.jdub.homelinux.org Signed-off-by: Ingo Molnar --- arch/x86/Kconfig | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'arch/x86/Kconfig') 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 -- cgit v1.2.2 From b53b5eda8194214928c8243d711a75dbf51809fc Mon Sep 17 00:00:00 2001 From: Josh Boyer Date: Tue, 5 Nov 2013 09:38:16 -0500 Subject: x86/cpu: Increase max CPU count to 8192 The MAXSMP option is intended to enable silly large numbers of CPUs for testing purposes. The current value of 4096 isn't very silly any longer as there are actual SGI machines that approach 6096 CPUs when taking HT into account. Increase the value to a nice round 8192 to account for this and allow for short term future increases. Signed-off-by: Josh Boyer Cc: prarit@redhat.com Cc: Russ Anderson Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/20131105143816.GK9944@hansolo.jdub.homelinux.org [ Tweaked it so that MAXSMP simply sets the maximum of the normal range. ] Signed-off-by: Ingo Molnar --- arch/x86/Kconfig | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/Kconfig') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index f03e428112eb..805469a57d9d 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -826,9 +826,9 @@ 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 && !CPUMASK_OFFSTACK - range 2 4096 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64 + range 2 8192 if SMP && !MAXSMP && CPUMASK_OFFSTACK && X86_64 default "1" if !SMP - default "4096" if MAXSMP + default "8192" if MAXSMP default "32" if SMP && (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP || X86_ES7000) default "8" if SMP ---help--- -- cgit v1.2.2