From patchwork Mon Jun 20 23:10:15 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 12888517 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7865C433EF for ; Mon, 20 Jun 2022 23:12:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346790AbiFTXMs (ORCPT ); Mon, 20 Jun 2022 19:12:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347048AbiFTXME (ORCPT ); Mon, 20 Jun 2022 19:12:04 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 241331D329; Mon, 20 Jun 2022 16:10:44 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id EAF37614FF; Mon, 20 Jun 2022 23:10:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F0781C341D5; Mon, 20 Jun 2022 23:10:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1655766632; bh=XyRgtSbvWle6eQPE5MOjMSTVqyJ2jrzKSkJQdZ5O6o8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JVqiBnRG+HmODhNEbcsRCQTKSU4+BRqs6o4v8vUYylnmqjXy6tJJYvTueMlIlnnnJ /ClUFh/bZdtS9/d/gPh841Xd1AJ5M5KDMPB3W00mBzdx+dSPHMUqk3vuuj7uE7LAL+ vuZFfOEB1Bh6Jh8/ZAu9acExFt6i3FO1ilPCnoE6SM6wNbsYVL+fdDL1Zrr47qeb49 mDkdabgELG75HDhaP9ZIu6KIWvn8RYbz7gG9LlZ5xnF2RNOZz1nk11Em8t5kuuwYbK HFYcv/Sr3QXnaXY5T6KhZchxRnQRMr8bVr4vMuRczyadsXN+RsdXvrNSDLgQSFNurM LYH/k8Abx4MHw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 5CD365C0D1B; Mon, 20 Jun 2022 16:10:31 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, Frederic Weisbecker , Peter Zijlstra , Thomas Gleixner , Neeraj Upadhyay , Uladzislau Rezki , Joel Fernandes , Boqun Feng , Nicolas Saenz Julienne , Marcelo Tosatti , Xiongfeng Wang , Yu Liao , Phil Auld , Paul Gortmaker , Alex Belits , "Paul E . McKenney" Subject: [PATCH rcu 09/23] context_tracking: Split user tracking Kconfig Date: Mon, 20 Jun 2022 16:10:15 -0700 Message-Id: <20220620231029.3844583-9-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20220620231027.GA3844372@paulmck-ThinkPad-P17-Gen-1> References: <20220620231027.GA3844372@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: Frederic Weisbecker Context tracking is going to be used not only to track user transitions but also idle/IRQs/NMIs. The user tracking part will then become a separate feature. Prepare Kconfig for that. Signed-off-by: Frederic Weisbecker Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Neeraj Upadhyay Cc: Uladzislau Rezki Cc: Joel Fernandes Cc: Boqun Feng Cc: Nicolas Saenz Julienne Cc: Marcelo Tosatti Cc: Xiongfeng Wang Cc: Yu Liao Cc: Phil Auld Cc: Paul Gortmaker Cc: Alex Belits Signed-off-by: Paul E. McKenney --- .../time/context-tracking/arch-support.txt | 6 ++-- arch/Kconfig | 4 +-- arch/arm/Kconfig | 2 +- arch/arm/kernel/entry-common.S | 4 +-- arch/arm/kernel/entry-header.S | 4 +-- arch/arm64/Kconfig | 2 +- arch/csky/Kconfig | 2 +- arch/csky/kernel/entry.S | 4 +-- arch/mips/Kconfig | 2 +- arch/powerpc/Kconfig | 2 +- arch/powerpc/include/asm/context_tracking.h | 2 +- arch/riscv/Kconfig | 2 +- arch/riscv/kernel/entry.S | 6 ++-- arch/sparc/Kconfig | 2 +- arch/sparc/kernel/rtrap_64.S | 2 +- arch/x86/Kconfig | 4 +-- include/linux/context_tracking.h | 12 +++---- include/linux/context_tracking_state.h | 4 +-- init/Kconfig | 4 +-- kernel/context_tracking.c | 6 +++- kernel/sched/core.c | 2 +- kernel/time/Kconfig | 31 ++++++++++++------- 22 files changed, 61 insertions(+), 48 deletions(-) diff --git a/Documentation/features/time/context-tracking/arch-support.txt b/Documentation/features/time/context-tracking/arch-support.txt index c9e0a16290e68..e59071a490901 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 fcf9a41a4ef5b..154b7b78da093 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 7630ba9cb6ccc..9acc6aac59126 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 7aa3ded4af929..37a0125fc9265 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 95def2b38d1ca..99411fa913501 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 1652a9800ebee..7c5dd2af9ca95 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 21d72b078eefc..f55ba1745f7b9 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 bc734d17c16f4..547b4cd1b24b4 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/mips/Kconfig b/arch/mips/Kconfig index db09d45d59ec7..9457894db2375 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 c2ce2e60c8f0f..874c8d81284ad 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 f2682b28b0502..4b63931c49e0e 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 32ffef9f6e5b4..29b46f2173457 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 12f6bba57e335..b9eda3fcbd6d7 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 ba449c47effd8..9232411a8821a 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 c5fd4b450d9b6..eef102765a7e2 100644 --- a/arch/sparc/kernel/rtrap_64.S +++ b/arch/sparc/kernel/rtrap_64.S @@ -15,7 +15,7 @@ #include #include -#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 be0b95e51df66..b0a6dbbb760bc 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/include/linux/context_tracking.h b/include/linux/context_tracking.h index 63259fece7c76..e35ae66b4794e 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -10,7 +10,7 @@ #include -#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 edc7b46376a6b..2b46afe105a96 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 c7900e8975f18..06454d19e2f0a 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 7f457a1a1b551..a6997daf27d10 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -22,6 +22,8 @@ #include #include +#ifdef CONFIG_CONTEXT_TRACKING_USER + #define CREATE_TRACE_POINTS #include @@ -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 da0bf6fe9ecdc..883167a57bf9d 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 27b7868b5c30d..41f99bcfe9e66 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.