Merge branch 'exynos-drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git...

[~andy/linux] / kernel / time / Kconfig

diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index b69692250af4a3ca47078e62d21c6ad2069e56af..70f27e89012b29d18b4aeb9c6e5c367d1b3955a5 100644 (file)
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -59,20 +59,88 @@ 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"