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-rw-r--r--kernel/time/Kconfig80
1 files changed, 74 insertions, 6 deletions
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index 24510d84efd..e4c07b0692b 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -64,20 +64,88 @@ config GENERIC_CMOS_UPDATE
if GENERIC_CLOCKEVENTS
menu "Timers subsystem"
-# Core internal switch. Selected by NO_HZ / HIGH_RES_TIMERS. This is
+# Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
# only related to the tick functionality. Oneshot clockevent devices
# are supported independ of this.
config TICK_ONESHOT
bool
-config NO_HZ
- bool "Tickless System (Dynamic Ticks)"
+config NO_HZ_COMMON
+ bool
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
select TICK_ONESHOT
+
+choice
+ prompt "Timer tick handling"
+ default NO_HZ_IDLE if NO_HZ
+
+config HZ_PERIODIC
+ bool "Periodic timer ticks (constant rate, no dynticks)"
+ help
+ This option keeps the tick running periodically at a constant
+ rate, even when the CPU doesn't need it.
+
+config NO_HZ_IDLE
+ bool "Idle dynticks system (tickless idle)"
+ depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
+ select NO_HZ_COMMON
+ help
+ This option enables a tickless idle system: timer interrupts
+ will only trigger on an as-needed basis when the system is idle.
+ This is usually interesting for energy saving.
+
+ Most of the time you want to say Y here.
+
+config NO_HZ_FULL
+ bool "Full dynticks system (tickless)"
+ # NO_HZ_COMMON dependency
+ depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
+ # We need at least one periodic CPU for timekeeping
+ depends on SMP
+ # RCU_USER_QS dependency
+ depends on HAVE_CONTEXT_TRACKING
+ # VIRT_CPU_ACCOUNTING_GEN dependency
+ depends on 64BIT
+ select NO_HZ_COMMON
+ select RCU_USER_QS
+ select RCU_NOCB_CPU
+ select VIRT_CPU_ACCOUNTING_GEN
+ select CONTEXT_TRACKING_FORCE
+ select IRQ_WORK
+ help
+ Adaptively try to shutdown the tick whenever possible, even when
+ the CPU is running tasks. Typically this requires running a single
+ task on the CPU. Chances for running tickless are maximized when
+ the task mostly runs in userspace and has few kernel activity.
+
+ You need to fill up the nohz_full boot parameter with the
+ desired range of dynticks CPUs.
+
+ This is implemented at the expense of some overhead in user <-> kernel
+ transitions: syscalls, exceptions and interrupts. Even when it's
+ dynamically off.
+
+ Say N.
+
+endchoice
+
+config NO_HZ_FULL_ALL
+ bool "Full dynticks system on all CPUs by default"
+ depends on NO_HZ_FULL
+ help
+ If the user doesn't pass the nohz_full boot option to
+ define the range of full dynticks CPUs, consider that all
+ CPUs in the system are full dynticks by default.
+ Note the boot CPU will still be kept outside the range to
+ handle the timekeeping duty.
+
+config NO_HZ
+ bool "Old Idle dynticks config"
+ depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
help
- This option enables a tickless system: timer interrupts will
- only trigger on an as-needed basis both when the system is
- busy and when the system is idle.
+ This is the old config entry that enables dynticks idle.
+ We keep it around for a little while to enforce backward
+ compatibility with older config files.
config HIGH_RES_TIMERS
bool "High Resolution Timer Support"