kernel/time/Kconfig

   1 #
   2 # Timer subsystem related configuration options
   3 #
   4
   5 # Options selectable by arch Kconfig
   6
   7 # Watchdog function for clocksources to detect instabilities
   8 config CLOCKSOURCE_WATCHDOG
   9         bool
  10
  11 # Architecture has extra clocksource data
  12 config ARCH_CLOCKSOURCE_DATA
  13         bool
  14
  15 # Platforms has a persistent clock
  16 config ALWAYS_USE_PERSISTENT_CLOCK
  17         bool
  18         default n
  19
  20 # Timekeeping vsyscall support
  21 config GENERIC_TIME_VSYSCALL
  22         bool
  23
  24 # Timekeeping vsyscall support
  25 config GENERIC_TIME_VSYSCALL_OLD
  26         bool
  27
  28 # ktime_t scalar 64bit nsec representation
  29 config KTIME_SCALAR
  30         bool
  31
  32 # Old style timekeeping
  33 config ARCH_USES_GETTIMEOFFSET
  34         bool
  35
  36 # The generic clock events infrastructure
  37 config GENERIC_CLOCKEVENTS
  38         bool
  39
  40 # Migration helper. Builds, but does not invoke
  41 config GENERIC_CLOCKEVENTS_BUILD
  42         bool
  43         default y
  44         depends on GENERIC_CLOCKEVENTS
  45
  46 # Architecture can handle broadcast in a driver-agnostic way
  47 config ARCH_HAS_TICK_BROADCAST
  48         bool
  49
  50 # Clockevents broadcasting infrastructure
  51 config GENERIC_CLOCKEVENTS_BROADCAST
  52         bool
  53         depends on GENERIC_CLOCKEVENTS
  54
  55 # Automatically adjust the min. reprogramming time for
  56 # clock event device
  57 config GENERIC_CLOCKEVENTS_MIN_ADJUST
  58         bool
  59
  60 # Generic update of CMOS clock
  61 config GENERIC_CMOS_UPDATE
  62         bool
  63
  64 if GENERIC_CLOCKEVENTS
  65 menu "Timers subsystem"
  66
  67 # Core internal switch. Selected by NO_HZ / HIGH_RES_TIMERS. This is
  68 # only related to the tick functionality. Oneshot clockevent devices
  69 # are supported independ of this.
  70 config TICK_ONESHOT
  71         bool
  72
  73 config NO_HZ
  74         bool "Tickless System (Dynamic Ticks)"
  75         depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
  76         select TICK_ONESHOT
  77         help
  78           This option enables a tickless system: timer interrupts will
  79           only trigger on an as-needed basis both when the system is
  80           busy and when the system is idle.
  81
  82 config NO_HZ_EXTENDED
  83        bool "Full dynticks system"
  84        depends on NO_HZ && RCU_USER_QS && VIRT_CPU_ACCOUNTING_GEN && RCU_NOCB_CPU && SMP
  85        select CONTEXT_TRACKING_FORCE
  86        help
  87          Adaptively try to shutdown the tick whenever possible, even when
  88          the CPU is running tasks. Typically this requires running a single
  89          task on the CPU. Chances for running tickless are maximized when
  90          the task mostly runs in userspace and has few kernel activity.
  91
  92          You need to fill up the nohz_extended boot parameter with the
  93          desired range of dynticks CPUs.
  94
  95          This is implemented at the expense of some overhead in user <-> kernel
  96          transitions: syscalls, exceptions and interrupts. Even when it's
  97          dynamically off.
  98
  99          Say N.
 100
 101 config HIGH_RES_TIMERS
 102         bool "High Resolution Timer Support"
 103         depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
 104         select TICK_ONESHOT
 105         help
 106           This option enables high resolution timer support. If your
 107           hardware is not capable then this option only increases
 108           the size of the kernel image.
 109
 110 endmenu
 111 endif