Messages in this thread Patch in this message | | | Subject | [PATCH] Configurable NR_CPUS for 2.5.24 | From | Robert Love <> | Date | 24 Jun 2002 15:06:40 -0400 |
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This is in 2.5-dj now and thus I have gotten a couple emails for a resync against 2.5 proper... so here we go, live from the Kernel Summit.
This patch implements a CONFIG_NR_CPUS that allows the user to specify a sane value for NR_CPUS in an effort to save memory and cycles. This is especially useful for debugging or other work where you have large per-CPU static structures. It also has a more appreciable benefit now that hotplug CPUs has more code using NR_CPUS vs smp_num_cpus.
This patch also allows each architecture to specify its own default NR_CPUS, allowing 64-bit arches to set their default to 64.
We need feedback on use of other-than-default NR_CPUS values (x86 is well tested) as well as use of the new 64 default on such architectures.
Oh, and to make Tom Rini happy I will accept patches for other architectures Config.help entries :)
Patch is against 2.5.24.
Robert Love
diff -urN linux-2.5.24/arch/alpha/config.in linux/arch/alpha/config.in --- linux-2.5.24/arch/alpha/config.in Thu Jun 20 15:53:47 2002 +++ linux/arch/alpha/config.in Thu Jun 20 16:35:45 2002 @@ -232,6 +232,7 @@ if [ "$CONFIG_SMP" = "y" ]; then define_bool CONFIG_HAVE_DEC_LOCK y + int 'Maximum number of CPUs (2-64)' CONFIG_NR_CPUS 64 fi if [ "$CONFIG_EXPERIMENTAL" = "y" ]; then diff -urN linux-2.5.24/arch/i386/Config.help linux/arch/i386/Config.help --- linux-2.5.24/arch/i386/Config.help Thu Jun 20 15:53:44 2002 +++ linux/arch/i386/Config.help Thu Jun 20 16:35:45 2002 @@ -25,6 +25,14 @@ If you don't know what to do here, say N. +CONFIG_NR_CPUS + This allows you to specify the maximum number of CPUs which this + kernel will support. The maximum supported value is 32 and the + minimum value which makes sense is 2. + + This is purely to save memory - each supported CPU adds + approximately eight kilobytes to the kernel image. + CONFIG_PREEMPT This option reduces the latency of the kernel when reacting to real-time or interactive events by allowing a low priority process to diff -urN linux-2.5.24/arch/i386/config.in linux/arch/i386/config.in --- linux-2.5.24/arch/i386/config.in Thu Jun 20 15:53:49 2002 +++ linux/arch/i386/config.in Thu Jun 20 16:35:45 2002 @@ -165,6 +165,7 @@ define_bool CONFIG_X86_IO_APIC y fi else + int 'Maximum number of CPUs (2-32)' CONFIG_NR_CPUS 32 bool 'Multiquad NUMA system' CONFIG_MULTIQUAD fi diff -urN linux-2.5.24/arch/i386/defconfig linux/arch/i386/defconfig --- linux-2.5.24/arch/i386/defconfig Thu Jun 20 15:53:45 2002 +++ linux/arch/i386/defconfig Thu Jun 20 16:35:45 2002 @@ -74,6 +74,7 @@ # CONFIG_PREEMPT is not set # CONFIG_MULTIQUAD is not set CONFIG_HAVE_DEC_LOCK=y +CONFIG_NR_CPUS=32 # # General options diff -urN linux-2.5.24/arch/ia64/config.in linux/arch/ia64/config.in --- linux-2.5.24/arch/ia64/config.in Thu Jun 20 15:53:53 2002 +++ linux/arch/ia64/config.in Thu Jun 20 16:35:45 2002 @@ -95,6 +95,10 @@ tristate '/proc/pal support' CONFIG_IA64_PALINFO tristate '/proc/efi/vars support' CONFIG_EFI_VARS +if [ "$CONFIG_SMP" = "y" ]; then + int 'Maximum number of CPUs (2-64)' CONFIG_NR_CPUS 64 +fi + tristate 'Kernel support for ELF binaries' CONFIG_BINFMT_ELF tristate 'Kernel support for MISC binaries' CONFIG_BINFMT_MISC diff -urN linux-2.5.24/arch/ia64/defconfig linux/arch/ia64/defconfig --- linux-2.5.24/arch/ia64/defconfig Thu Jun 20 15:53:44 2002 +++ linux/arch/ia64/defconfig Thu Jun 20 16:35:45 2002 @@ -61,6 +61,7 @@ CONFIG_EFI_VARS=y CONFIG_BINFMT_ELF=y # CONFIG_BINFMT_MISC is not set +CONFIG_NR_CPUS=64 # # ACPI Support diff -urN linux-2.5.24/arch/mips/config.in linux/arch/mips/config.in --- linux-2.5.24/arch/mips/config.in Thu Jun 20 15:53:54 2002 +++ linux/arch/mips/config.in Thu Jun 20 16:35:45 2002 @@ -500,6 +500,8 @@ bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ if [ "$CONFIG_SMP" != "y" ]; then bool 'Run uncached' CONFIG_MIPS_UNCACHED +else + int 'Maximum number of CPUs (2-32)' CONFIG_NR_CPUS 32 fi endmenu diff -urN linux-2.5.24/arch/mips64/config.in linux/arch/mips64/config.in --- linux-2.5.24/arch/mips64/config.in Thu Jun 20 15:53:45 2002 +++ linux/arch/mips64/config.in Thu Jun 20 16:35:45 2002 @@ -245,6 +245,8 @@ bool 'Magic SysRq key' CONFIG_MAGIC_SYSRQ if [ "$CONFIG_SMP" != "y" ]; then bool 'Run uncached' CONFIG_MIPS_UNCACHED +else + int 'Maximum number of CPUs (2-64)' CONFIG_NR_CPUS 64 fi endmenu diff -urN linux-2.5.24/arch/mips64/defconfig linux/arch/mips64/defconfig --- linux-2.5.24/arch/mips64/defconfig Thu Jun 20 15:53:47 2002 +++ linux/arch/mips64/defconfig Thu Jun 20 16:35:45 2002 @@ -32,6 +32,7 @@ # CONFIG_EISA is not set # CONFIG_MCA is not set # CONFIG_SBUS is not set +CONFIG_NR_CPUS=64 # # CPU selection diff -urN linux-2.5.24/arch/parisc/config.in linux/arch/parisc/config.in --- linux-2.5.24/arch/parisc/config.in Thu Jun 20 15:53:57 2002 +++ linux/arch/parisc/config.in Thu Jun 20 16:35:45 2002 @@ -18,6 +18,10 @@ # bool 'Symmetric multi-processing support' CONFIG_SMP define_bool CONFIG_SMP n +if [ "$CONFIG_SMP" = "y" ]; then + int 'Maximum number of CPUs (2-32)' CONFIG_NR_CPUS 32 +fi + bool 'Kernel Debugger support' CONFIG_KWDB # define_bool CONFIG_KWDB n diff -urN linux-2.5.24/arch/ppc/config.in linux/arch/ppc/config.in --- linux-2.5.24/arch/ppc/config.in Thu Jun 20 15:53:41 2002 +++ linux/arch/ppc/config.in Thu Jun 20 16:35:45 2002 @@ -172,6 +172,7 @@ bool 'Symmetric multi-processing support' CONFIG_SMP if [ "$CONFIG_SMP" = "y" ]; then bool ' Distribute interrupts on all CPUs by default' CONFIG_IRQ_ALL_CPUS + int 'Maximum number of CPUs (2-32)' CONFIG_NR_CPUS 32 fi if [ "$CONFIG_SMP" != "y" ]; then bool 'Preemptible Kernel' CONFIG_PREEMPT diff -urN linux-2.5.24/arch/ppc64/config.in linux/arch/ppc64/config.in --- linux-2.5.24/arch/ppc64/config.in Thu Jun 20 15:53:45 2002 +++ linux/arch/ppc64/config.in Thu Jun 20 16:35:45 2002 @@ -21,6 +21,7 @@ bool 'Symmetric multi-processing support' CONFIG_SMP if [ "$CONFIG_SMP" = "y" ]; then bool ' Distribute interrupts on all CPUs by default' CONFIG_IRQ_ALL_CPUS + int 'Maximum number of CPUs (2-64)' CONFIG_NR_CPUS 64 if [ "$CONFIG_PPC_PSERIES" = "y" ]; then bool ' Hardware multithreading' CONFIG_HMT fi diff -urN linux-2.5.24/arch/ppc64/defconfig linux/arch/ppc64/defconfig --- linux-2.5.24/arch/ppc64/defconfig Thu Jun 20 15:53:48 2002 +++ linux/arch/ppc64/defconfig Thu Jun 20 16:35:45 2002 @@ -38,6 +38,7 @@ CONFIG_IRQ_ALL_CPUS=y # CONFIG_HMT is not set # CONFIG_PREEMPT is not set +CONFIG_NR_CPUS=64 # # General setup diff -urN linux-2.5.24/arch/s390/config.in linux/arch/s390/config.in --- linux-2.5.24/arch/s390/config.in Thu Jun 20 15:53:47 2002 +++ linux/arch/s390/config.in Thu Jun 20 16:35:45 2002 @@ -20,6 +20,9 @@ comment 'Processor type and features' bool 'Symmetric multi-processing support' CONFIG_SMP bool 'IEEE FPU emulation' CONFIG_MATHEMU +if [ "$CONFIG_SMP" = "y" ]; then + int 'Maximum number of CPUs (2-32)' CONFIG_NR_CPUS 32 +fi endmenu mainmenu_option next_comment diff -urN linux-2.5.24/arch/s390/defconfig linux/arch/s390/defconfig --- linux-2.5.24/arch/s390/defconfig Thu Jun 20 15:53:56 2002 +++ linux/arch/s390/defconfig Thu Jun 20 16:35:45 2002 @@ -35,6 +35,7 @@ # CONFIG_SMP=y CONFIG_MATHEMU=y +CONFIG_NR_CPUS=64 # # Base setup diff -urN linux-2.5.24/arch/s390x/config.in linux/arch/s390x/config.in --- linux-2.5.24/arch/s390x/config.in Thu Jun 20 15:53:44 2002 +++ linux/arch/s390x/config.in Thu Jun 20 16:35:45 2002 @@ -19,6 +19,9 @@ mainmenu_option next_comment comment 'Processor type and features' bool 'Symmetric multi-processing support' CONFIG_SMP +if [ "$CONFIG_SMP" = "y" ]; then + int 'Maximum number of CPUs (2-64)' CONFIG_NR_CPUS 64 +fi bool 'Kernel support for 31 bit emulation' CONFIG_S390_SUPPORT if [ "$CONFIG_S390_SUPPORT" = "y" ]; then tristate 'Kernel support for 31 bit ELF binaries' CONFIG_BINFMT_ELF32 diff -urN linux-2.5.24/arch/s390x/defconfig linux/arch/s390x/defconfig --- linux-2.5.24/arch/s390x/defconfig Thu Jun 20 15:53:41 2002 +++ linux/arch/s390x/defconfig Thu Jun 20 16:35:45 2002 @@ -36,6 +36,7 @@ CONFIG_SMP=y CONFIG_S390_SUPPORT=y CONFIG_BINFMT_ELF32=y +CONFIG_NR_CPUS=64 # # Base setup diff -urN linux-2.5.24/arch/sparc/config.in linux/arch/sparc/config.in --- linux-2.5.24/arch/sparc/config.in Thu Jun 20 15:53:44 2002 +++ linux/arch/sparc/config.in Thu Jun 20 16:35:45 2002 @@ -17,6 +17,10 @@ bool 'Symmetric multi-processing support (does not work on sun4/sun4c)' CONFIG_SMP +if [ "$CONFIG_SMP" = "y" ]; then + int 'Maximum number of CPUs (2-32)' CONFIG_NR_CPUS 32 +fi + # Identify this as a Sparc32 build define_bool CONFIG_SPARC32 y diff -urN linux-2.5.24/arch/sparc64/config.in linux/arch/sparc64/config.in --- linux-2.5.24/arch/sparc64/config.in Thu Jun 20 15:53:49 2002 +++ linux/arch/sparc64/config.in Thu Jun 20 16:35:45 2002 @@ -17,6 +17,10 @@ bool 'Symmetric multi-processing support' CONFIG_SMP bool 'Preemptible Kernel' CONFIG_PREEMPT +if [ "$CONFIG_SMP" = "y" ]; then + int 'Maximum number of CPUs (2-64)' CONFIG_NR_CPUS 64 +fi + # Identify this as a Sparc64 build define_bool CONFIG_SPARC64 y diff -urN linux-2.5.24/arch/sparc64/defconfig linux/arch/sparc64/defconfig --- linux-2.5.24/arch/sparc64/defconfig Thu Jun 20 15:53:49 2002 +++ linux/arch/sparc64/defconfig Thu Jun 20 16:35:45 2002 @@ -63,6 +63,7 @@ CONFIG_BINFMT_MISC=m # CONFIG_SUNOS_EMUL is not set CONFIG_SOLARIS_EMUL=m +CONFIG_NR_CPUS=64 # # Parallel port support diff -urN linux-2.5.24/arch/x86_64/config.in linux/arch/x86_64/config.in --- linux-2.5.24/arch/x86_64/config.in Thu Jun 20 15:53:47 2002 +++ linux/arch/x86_64/config.in Thu Jun 20 16:35:45 2002 @@ -54,6 +54,7 @@ fi if [ "$CONFIG_SMP" = "y" ]; then define_bool CONFIG_HAVE_DEC_LOCK y + int 'Maximum number of CPUs (2-64)' CONFIG_NR_CPUS 64 fi define_bool CONFIG_X86_MCE y diff -urN linux-2.5.24/arch/x86_64/defconfig linux/arch/x86_64/defconfig --- linux-2.5.24/arch/x86_64/defconfig Thu Jun 20 15:53:55 2002 +++ linux/arch/x86_64/defconfig Thu Jun 20 16:35:45 2002 @@ -51,6 +51,7 @@ CONFIG_HAVE_DEC_LOCK=y CONFIG_X86_MCE=y # CONFIG_X86_MCE_NONFATAL is not set +CONFIG_NR_CPUS=64 # # Power management options diff -urN linux-2.5.24/include/linux/threads.h linux/include/linux/threads.h --- linux-2.5.24/include/linux/threads.h Thu Jun 20 15:53:42 2002 +++ linux/include/linux/threads.h Thu Jun 20 16:35:45 2002 @@ -8,10 +8,16 @@ * /proc/sys/kernel/threads-max. */ +/* + * Maximum supported processors that can run under SMP. This value is + * set via configure setting. The maximum is equal to the size of the + * bitmasks used on that platform, i.e. 32 or 64. Setting this smaller + * saves quite a bit of memory. + */ #ifdef CONFIG_SMP -#define NR_CPUS 32 /* Max processors that can be running in SMP */ +#define NR_CPUS CONFIG_NR_CPUS #else -#define NR_CPUS 1 +#define NR_CPUS 1 #endif #define MIN_THREADS_LEFT_FOR_ROOT 4 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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