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Message-Id: <20220608144037.1765000-8-frederic@kernel.org>
Date: Wed, 8 Jun 2022 16:40:24 +0200
From: Frederic Weisbecker <frederic@...nel.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Frederic Weisbecker <frederic@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Phil Auld <pauld@...hat.com>,
Alex Belits <abelits@...vell.com>,
Nicolas Saenz Julienne <nsaenz@...nel.org>,
Xiongfeng Wang <wangxiongfeng2@...wei.com>,
Neeraj Upadhyay <quic_neeraju@...cinc.com>,
Thomas Gleixner <tglx@...utronix.de>,
Yu Liao <liaoyu15@...wei.com>,
Boqun Feng <boqun.feng@...il.com>,
"Paul E . McKenney" <paulmck@...nel.org>,
Marcelo Tosatti <mtosatti@...hat.com>,
Paul Gortmaker <paul.gortmaker@...driver.com>,
Uladzislau Rezki <uladzislau.rezki@...y.com>,
Joel Fernandes <joel@...lfernandes.org>
Subject: [PATCH 07/20] context_tracking: Split user tracking Kconfig
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 <frederic@...nel.org>
Cc: Paul E. McKenney <paulmck@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Neeraj Upadhyay <quic_neeraju@...cinc.com>
Cc: Uladzislau Rezki <uladzislau.rezki@...y.com>
Cc: Joel Fernandes <joel@...lfernandes.org>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: Nicolas Saenz Julienne <nsaenz@...nel.org>
Cc: Marcelo Tosatti <mtosatti@...hat.com>
Cc: Xiongfeng Wang <wangxiongfeng2@...wei.com>
Cc: Yu Liao<liaoyu15@...wei.com>
Cc: Phil Auld <pauld@...hat.com>
Cc: Paul Gortmaker<paul.gortmaker@...driver.com>
Cc: Alex Belits <abelits@...vell.com>
---
.../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 bb1c1801553e..59ec30c84541 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 1bf29ce754af..7a8cd4d67d9c 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -769,7 +769,7 @@ 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
@@ -780,7 +780,7 @@ 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 2e8091e2d8a8..64eb31946598 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 90d40f4d56cf..393d3945a43f 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 0c14dcc43e58..8a54ff24bed0 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -367,7 +367,7 @@ 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
@@ -379,7 +379,7 @@ 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 57c4c995965f..6e8757b89a54 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -171,7 +171,7 @@ 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 75ef86605d69..171b59901214 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/mips/Kconfig b/arch/mips/Kconfig
index de3b32a507d2..d0048cddd558 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 174edabb74fa..f2fddc09a345 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -197,7 +197,7 @@ 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 00fd9c548f26..08316de9fa9f 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -83,7 +83,7 @@ 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 ecd132af2edf..fba900eaa0b8 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)
@@ -255,7 +255,7 @@ 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 9200bc04701c..be50eae3ab0d 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 b0142e01002e..368a1c5cbb08 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -185,8 +185,8 @@ 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 STACK_VALIDATION
select HAVE_BUILDTIME_MCOUNT_SORT
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 02be3ac2040d..913acfee5dbf 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 inline bool context_tracking_enabled(void) { return false; }
static inline bool context_tracking_enabled_cpu(int cpu) { return false; }
static 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 ddcbefe535e9..3d88ecadf771 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -502,11 +502,11 @@ 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 ccf18032e742..9e2797d4c41e 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>
@@ -253,7 +255,7 @@ 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;
@@ -262,3 +264,5 @@ 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 c1749f6561ef..a4419ec8bcbe 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6515,7 +6515,7 @@ 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.
--
2.25.1
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