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authorLinus Torvalds <torvalds@linux-foundation.org>2020-03-30 18:29:05 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-03-30 18:29:05 -0700
commit336622e9fce7a0b8243e1cd9f6e1c24d96f13cd8 (patch)
treea92d7a0e419e825d398b64252493224e37cb0ca0 /arch/Kconfig
parent992a1a3b45b5c0b6e69ecc2a3f32b0d02da28d58 (diff)
parente4970c9c54d7cb4edc24d82ed27aef69aaf593de (diff)
downloadlinux-336622e9fce7a0b8243e1cd9f6e1c24d96f13cd8.tar.bz2
Merge tag 'timers-nohz-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull NOHZ update from Thomas Gleixner: "Remove TIF_NOHZ from three architectures These architectures use a static key to decide whether context tracking needs to be invoked and the TIF_NOHZ flag just causes a pointless slowpath execution for nothing" * tag 'timers-nohz-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: arm64: Remove TIF_NOHZ arm: Remove TIF_NOHZ x86: Remove TIF_NOHZ context-tracking: Introduce CONFIG_HAVE_TIF_NOHZ x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY
Diffstat (limited to 'arch/Kconfig')
-rw-r--r--arch/Kconfig16
1 files changed, 11 insertions, 5 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 17fe351cdde0..516f2b05bd66 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -540,11 +540,17 @@ config HAVE_CONTEXT_TRACKING
help
Provide kernel/user boundaries probes necessary for subsystems
that need it, such as userspace RCU extended quiescent state.
- Syscalls need to be wrapped inside user_exit()-user_enter() through
- the slow path using TIF_NOHZ flag. Exceptions handlers must be
- wrapped as well. Irqs are already protected inside
- rcu_irq_enter/rcu_irq_exit() but preemption or signal handling on
- irq exit still need to be protected.
+ Syscalls need to be wrapped inside user_exit()-user_enter(), either
+ optimized behind static key or through the slow path using TIF_NOHZ
+ flag. Exceptions handlers must be wrapped as well. Irqs are already
+ protected inside rcu_irq_enter/rcu_irq_exit() but preemption or signal
+ handling on irq exit still need to be protected.
+
+config HAVE_TIF_NOHZ
+ bool
+ help
+ Arch relies on TIF_NOHZ and syscall slow path to implement context
+ tracking calls to user_enter()/user_exit().
config HAVE_VIRT_CPU_ACCOUNTING
bool