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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-03-30 18:29:05 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-03-30 18:29:05 -0700 |
| commit | 336622e9fce7a0b8243e1cd9f6e1c24d96f13cd8 (patch) | |
| tree | a92d7a0e419e825d398b64252493224e37cb0ca0 /arch/Kconfig | |
| parent | 992a1a3b45b5c0b6e69ecc2a3f32b0d02da28d58 (diff) | |
| parent | e4970c9c54d7cb4edc24d82ed27aef69aaf593de (diff) | |
| download | linux-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/Kconfig | 16 |
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 |