diff options
| -rw-r--r-- | Documentation/features/time/context-tracking/arch-support.txt | 6 | ||||
| -rw-r--r-- | arch/Kconfig | 4 | ||||
| -rw-r--r-- | arch/arm/Kconfig | 2 | ||||
| -rw-r--r-- | arch/arm/kernel/entry-common.S | 4 | ||||
| -rw-r--r-- | arch/arm/kernel/entry-header.S | 4 | ||||
| -rw-r--r-- | arch/arm64/Kconfig | 2 | ||||
| -rw-r--r-- | arch/csky/Kconfig | 2 | ||||
| -rw-r--r-- | arch/csky/kernel/entry.S | 4 | ||||
| -rw-r--r-- | arch/loongarch/Kconfig | 2 | ||||
| -rw-r--r-- | arch/mips/Kconfig | 2 | ||||
| -rw-r--r-- | arch/powerpc/Kconfig | 2 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/context_tracking.h | 2 | ||||
| -rw-r--r-- | arch/riscv/Kconfig | 2 | ||||
| -rw-r--r-- | arch/riscv/kernel/entry.S | 6 | ||||
| -rw-r--r-- | arch/sparc/Kconfig | 2 | ||||
| -rw-r--r-- | arch/sparc/kernel/rtrap_64.S | 2 | ||||
| -rw-r--r-- | arch/x86/Kconfig | 4 | ||||
| -rw-r--r-- | arch/xtensa/Kconfig | 2 | ||||
| -rw-r--r-- | arch/xtensa/kernel/entry.S | 4 | ||||
| -rw-r--r-- | include/linux/context_tracking.h | 12 | ||||
| -rw-r--r-- | include/linux/context_tracking_state.h | 4 | ||||
| -rw-r--r-- | init/Kconfig | 4 | ||||
| -rw-r--r-- | kernel/context_tracking.c | 6 | ||||
| -rw-r--r-- | kernel/sched/core.c | 2 | ||||
| -rw-r--r-- | kernel/time/Kconfig | 31 |
25 files changed, 65 insertions, 52 deletions
diff --git a/Documentation/features/time/context-tracking/arch-support.txt b/Documentation/features/time/context-tracking/arch-support.txt index c9e0a16290e6..e59071a49090 100644 --- a/Documentation/features/time/context-tracking/arch-support.txt +++ b/Documentation/features/time/context-tracking/arch-support.txt @@ -1,7 +1,7 @@ # -# Feature name: context-tracking -# Kconfig: HAVE_CONTEXT_TRACKING -# description: arch supports context tracking for NO_HZ_FULL +# Feature name: user-context-tracking +# Kconfig: HAVE_CONTEXT_TRACKING_USER +# description: arch supports user context tracking for NO_HZ_FULL # ----------------------- | arch |status| diff --git a/arch/Kconfig b/arch/Kconfig index fcf9a41a4ef5..154b7b78da09 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -774,7 +774,7 @@ config HAVE_ARCH_WITHIN_STACK_FRAMES and similar) by implementing an inline arch_within_stack_frames(), which is used by CONFIG_HARDENED_USERCOPY. -config HAVE_CONTEXT_TRACKING +config HAVE_CONTEXT_TRACKING_USER bool help Provide kernel/user boundaries probes necessary for subsystems @@ -785,7 +785,7 @@ config HAVE_CONTEXT_TRACKING protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on irq exit still need to be protected. -config HAVE_CONTEXT_TRACKING_OFFSTACK +config HAVE_CONTEXT_TRACKING_USER_OFFSTACK bool help Architecture neither relies on exception_enter()/exception_exit() diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 7630ba9cb6cc..9acc6aac5912 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -84,7 +84,7 @@ config ARM select HAVE_ARCH_TRANSPARENT_HUGEPAGE if ARM_LPAE select HAVE_ARM_SMCCC if CPU_V7 select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32 - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_C_RECORDMCOUNT select HAVE_BUILDTIME_MCOUNT_SORT select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 7aa3ded4af92..37a0125fc926 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -28,7 +28,7 @@ #include "entry-header.S" saved_psr .req r8 -#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING) +#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER) saved_pc .req r9 #define TRACE(x...) x #else @@ -38,7 +38,7 @@ saved_pc .req lr .section .entry.text,"ax",%progbits .align 5 -#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING) || \ +#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING_USER) || \ IS_ENABLED(CONFIG_DEBUG_RSEQ)) /* * This is the fast syscall return path. We do as little as possible here, diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 95def2b38d1c..99411fa91350 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -366,7 +366,7 @@ ALT_UP_B(.L1_\@) * between user and kernel mode. */ .macro ct_user_exit, save = 1 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER .if \save stmdb sp!, {r0-r3, ip, lr} bl user_exit_callable @@ -378,7 +378,7 @@ ALT_UP_B(.L1_\@) .endm .macro ct_user_enter, save = 1 -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER .if \save stmdb sp!, {r0-r3, ip, lr} bl user_enter_callable diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1652a9800ebe..7c5dd2af9ca9 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -174,7 +174,7 @@ config ARM64 select HAVE_C_RECORDMCOUNT select HAVE_CMPXCHG_DOUBLE select HAVE_CMPXCHG_LOCAL - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS select HAVE_DYNAMIC_FTRACE diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig index 21d72b078eef..f55ba1745f7b 100644 --- a/arch/csky/Kconfig +++ b/arch/csky/Kconfig @@ -42,7 +42,7 @@ config CSKY select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_MMAP_RND_BITS select HAVE_ARCH_SECCOMP_FILTER - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_VIRT_CPU_ACCOUNTING_GEN select HAVE_DEBUG_BUGVERBOSE select HAVE_DEBUG_KMEMLEAK diff --git a/arch/csky/kernel/entry.S b/arch/csky/kernel/entry.S index bc734d17c16f..547b4cd1b24b 100644 --- a/arch/csky/kernel/entry.S +++ b/arch/csky/kernel/entry.S @@ -19,7 +19,7 @@ .endm .macro context_tracking -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER mfcr a0, epsr btsti a0, 31 bt 1f @@ -159,7 +159,7 @@ ret_from_exception: and r10, r9 cmpnei r10, 0 bt exit_work -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER jbsr user_enter_callable #endif 1: diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index 1920d52653b4..130dc65f3c85 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -76,7 +76,7 @@ config LOONGARCH select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE select HAVE_ASM_MODVERSIONS - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_COPY_THREAD_TLS select HAVE_DEBUG_STACKOVERFLOW select HAVE_DMA_CONTIGUOUS diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index db09d45d59ec..9457894db237 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -56,7 +56,7 @@ config MIPS select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE if CPU_SUPPORTS_HUGEPAGES select HAVE_ASM_MODVERSIONS - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_TIF_NOHZ select HAVE_C_RECORDMCOUNT select HAVE_DEBUG_KMEMLEAK diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index c2ce2e60c8f0..874c8d81284a 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -202,7 +202,7 @@ config PPC select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_TRACEHOOK select HAVE_ASM_MODVERSIONS - select HAVE_CONTEXT_TRACKING if PPC64 + select HAVE_CONTEXT_TRACKING_USER if PPC64 select HAVE_C_RECORDMCOUNT select HAVE_DEBUG_KMEMLEAK select HAVE_DEBUG_STACKOVERFLOW diff --git a/arch/powerpc/include/asm/context_tracking.h b/arch/powerpc/include/asm/context_tracking.h index f2682b28b050..4b63931c49e0 100644 --- a/arch/powerpc/include/asm/context_tracking.h +++ b/arch/powerpc/include/asm/context_tracking.h @@ -2,7 +2,7 @@ #ifndef _ASM_POWERPC_CONTEXT_TRACKING_H #define _ASM_POWERPC_CONTEXT_TRACKING_H -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER #define SCHEDULE_USER bl schedule_user #else #define SCHEDULE_USER bl schedule diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 32ffef9f6e5b..29b46f217345 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -86,7 +86,7 @@ config RISCV select HAVE_ARCH_THREAD_STRUCT_WHITELIST select HAVE_ARCH_VMAP_STACK if MMU && 64BIT select HAVE_ASM_MODVERSIONS - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS if MMU select HAVE_EBPF_JIT if MMU diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 12f6bba57e33..b9eda3fcbd6d 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -111,7 +111,7 @@ _save_context: call __trace_hardirqs_off #endif -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER /* If previous state is in user mode, call user_exit_callable(). */ li a0, SR_PP and a0, s1, a0 @@ -176,7 +176,7 @@ handle_syscall: */ csrs CSR_STATUS, SR_IE #endif -#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING) +#if defined(CONFIG_TRACE_IRQFLAGS) || defined(CONFIG_CONTEXT_TRACKING_USER) /* Recover a0 - a7 for system calls */ REG_L a0, PT_A0(sp) REG_L a1, PT_A1(sp) @@ -269,7 +269,7 @@ resume_userspace: andi s1, s0, _TIF_WORK_MASK bnez s1, work_pending -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER call user_enter_callable #endif diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index ba449c47effd..9232411a8821 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -71,7 +71,7 @@ config SPARC64 select HAVE_DYNAMIC_FTRACE select HAVE_FTRACE_MCOUNT_RECORD select HAVE_SYSCALL_TRACEPOINTS - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_TIF_NOHZ select HAVE_DEBUG_KMEMLEAK select IOMMU_HELPER diff --git a/arch/sparc/kernel/rtrap_64.S b/arch/sparc/kernel/rtrap_64.S index c5fd4b450d9b..eef102765a7e 100644 --- a/arch/sparc/kernel/rtrap_64.S +++ b/arch/sparc/kernel/rtrap_64.S @@ -15,7 +15,7 @@ #include <asm/visasm.h> #include <asm/processor.h> -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER # define SCHEDULE_USER schedule_user #else # define SCHEDULE_USER schedule diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index be0b95e51df6..b0a6dbbb760b 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -186,8 +186,8 @@ config X86 select HAVE_ASM_MODVERSIONS select HAVE_CMPXCHG_DOUBLE select HAVE_CMPXCHG_LOCAL - select HAVE_CONTEXT_TRACKING if X86_64 - select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER if X86_64 + select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if HAVE_CONTEXT_TRACKING_USER select HAVE_C_RECORDMCOUNT select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL select HAVE_BUILDTIME_MCOUNT_SORT diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index 0b0f0172cced..7927fed7bc83 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -33,7 +33,7 @@ config XTENSA select HAVE_ARCH_KCSAN select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_TRACEHOOK - select HAVE_CONTEXT_TRACKING + select HAVE_CONTEXT_TRACKING_USER select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS select HAVE_EXIT_THREAD diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S index d72bcafae90c..fb67d85116e4 100644 --- a/arch/xtensa/kernel/entry.S +++ b/arch/xtensa/kernel/entry.S @@ -455,7 +455,7 @@ KABI_W or a3, a3, a2 abi_call trace_hardirqs_off 1: #endif -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER l32i abi_tmp0, a1, PT_PS bbci.l abi_tmp0, PS_UM_BIT, 1f abi_call user_exit_callable @@ -544,7 +544,7 @@ common_exception_return: j .Lrestore_state .Lexit_tif_loop_user: -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER abi_call user_enter_callable #endif #ifdef CONFIG_HAVE_HW_BREAKPOINT diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index 63259fece7c7..e35ae66b4794 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -10,7 +10,7 @@ #include <asm/ptrace.h> -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER extern void ct_cpu_track_user(int cpu); /* Called with interrupts disabled. */ @@ -52,7 +52,7 @@ static inline enum ctx_state exception_enter(void) { enum ctx_state prev_ctx; - if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) || + if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) || !context_tracking_enabled()) return 0; @@ -65,7 +65,7 @@ static inline enum ctx_state exception_enter(void) static inline void exception_exit(enum ctx_state prev_ctx) { - if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) && + if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) && context_tracking_enabled()) { if (prev_ctx != CONTEXT_KERNEL) ct_user_enter(prev_ctx); @@ -109,14 +109,14 @@ static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; } static __always_inline bool context_tracking_guest_enter(void) { return false; } static inline void context_tracking_guest_exit(void) { } -#endif /* !CONFIG_CONTEXT_TRACKING */ +#endif /* !CONFIG_CONTEXT_TRACKING_USER */ #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond)) -#ifdef CONFIG_CONTEXT_TRACKING_FORCE +#ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE extern void context_tracking_init(void); #else static inline void context_tracking_init(void) { } -#endif /* CONFIG_CONTEXT_TRACKING_FORCE */ +#endif /* CONFIG_CONTEXT_TRACKING_USER_FORCE */ #endif diff --git a/include/linux/context_tracking_state.h b/include/linux/context_tracking_state.h index edc7b46376a6..2b46afe105a9 100644 --- a/include/linux/context_tracking_state.h +++ b/include/linux/context_tracking_state.h @@ -22,7 +22,7 @@ struct context_tracking { } state; }; -#ifdef CONFIG_CONTEXT_TRACKING +#ifdef CONFIG_CONTEXT_TRACKING_USER extern struct static_key_false context_tracking_key; DECLARE_PER_CPU(struct context_tracking, context_tracking); @@ -45,6 +45,6 @@ static inline bool context_tracking_enabled_this_cpu(void) static __always_inline bool context_tracking_enabled(void) { return false; } static __always_inline bool context_tracking_enabled_cpu(int cpu) { return false; } static __always_inline bool context_tracking_enabled_this_cpu(void) { return false; } -#endif /* CONFIG_CONTEXT_TRACKING */ +#endif /* CONFIG_CONTEXT_TRACKING_USER */ #endif diff --git a/init/Kconfig b/init/Kconfig index c7900e8975f1..06454d19e2f0 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -494,11 +494,11 @@ config VIRT_CPU_ACCOUNTING_NATIVE config VIRT_CPU_ACCOUNTING_GEN bool "Full dynticks CPU time accounting" - depends on HAVE_CONTEXT_TRACKING + depends on HAVE_CONTEXT_TRACKING_USER depends on HAVE_VIRT_CPU_ACCOUNTING_GEN depends on GENERIC_CLOCKEVENTS select VIRT_CPU_ACCOUNTING - select CONTEXT_TRACKING + select CONTEXT_TRACKING_USER help Select this option to enable task and CPU time accounting on full dynticks systems. This accounting is implemented by watching every diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index d361bd52e4e1..f3dec1be2bf6 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -22,6 +22,8 @@ #include <linux/export.h> #include <linux/kprobes.h> +#ifdef CONFIG_CONTEXT_TRACKING_USER + #define CREATE_TRACE_POINTS #include <trace/events/context_tracking.h> @@ -252,7 +254,7 @@ void __init ct_cpu_track_user(int cpu) initialized = true; } -#ifdef CONFIG_CONTEXT_TRACKING_FORCE +#ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE void __init context_tracking_init(void) { int cpu; @@ -261,3 +263,5 @@ void __init context_tracking_init(void) ct_cpu_track_user(cpu); } #endif + +#endif /* #ifdef CONFIG_CONTEXT_TRACKING_USER */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index da0bf6fe9ecd..883167a57bf9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6559,7 +6559,7 @@ void __sched schedule_idle(void) } while (need_resched()); } -#if defined(CONFIG_CONTEXT_TRACKING) && !defined(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) +#if defined(CONFIG_CONTEXT_TRACKING_USER) && !defined(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) asmlinkage __visible void __sched schedule_user(void) { /* diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 27b7868b5c30..41f99bcfe9e6 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -73,6 +73,9 @@ config TIME_KUNIT_TEST If unsure, say N. +config CONTEXT_TRACKING + bool + if GENERIC_CLOCKEVENTS menu "Timers subsystem" @@ -111,7 +114,7 @@ config NO_HZ_FULL # NO_HZ_COMMON dependency # We need at least one periodic CPU for timekeeping depends on SMP - depends on HAVE_CONTEXT_TRACKING + depends on HAVE_CONTEXT_TRACKING_USER # VIRT_CPU_ACCOUNTING_GEN dependency depends on HAVE_VIRT_CPU_ACCOUNTING_GEN select NO_HZ_COMMON @@ -137,31 +140,37 @@ config NO_HZ_FULL endchoice -config CONTEXT_TRACKING - bool +config CONTEXT_TRACKING_USER + bool + depends on HAVE_CONTEXT_TRACKING_USER + select CONTEXT_TRACKING + help + Track transitions between kernel and user on behalf of RCU and + tickless cputime accounting. The former case relies on context + tracking to enter/exit RCU extended quiescent states. -config CONTEXT_TRACKING_FORCE - bool "Force context tracking" - depends on CONTEXT_TRACKING +config CONTEXT_TRACKING_USER_FORCE + bool "Force user context tracking" + depends on CONTEXT_TRACKING_USER default y if !NO_HZ_FULL help The major pre-requirement for full dynticks to work is to - support the context tracking subsystem. But there are also + support the user context tracking subsystem. But there are also other dependencies to provide in order to make the full dynticks working. This option stands for testing when an arch implements the - context tracking backend but doesn't yet fulfill all the + user context tracking backend but doesn't yet fulfill all the requirements to make the full dynticks feature working. Without the full dynticks, there is no way to test the support - for context tracking and the subsystems that rely on it: RCU + for user context tracking and the subsystems that rely on it: RCU userspace extended quiescent state and tickless cputime accounting. This option copes with the absence of the full - dynticks subsystem by forcing the context tracking on all + dynticks subsystem by forcing the user context tracking on all CPUs in the system. Say Y only if you're working on the development of an - architecture backend for the context tracking. + architecture backend for the user context tracking. Say N otherwise, this option brings an overhead that you don't want in production. |