kernel/Kconfig.preempt

   1
   2 choice
   3         prompt "Preemption Model"
   4         default PREEMPT_NONE
   5
   6 config PREEMPT_NONE
   7         bool "No Forced Preemption (Server)"
   8         help
   9           This is the traditional Linux preemption model, geared towards
  10           throughput. It will still provide good latencies most of the
  11           time, but there are no guarantees and occasional longer delays
  12           are possible.
  13
  14           Select this option if you are building a kernel for a server or
  15           scientific/computation system, or if you want to maximize the
  16           raw processing power of the kernel, irrespective of scheduling
  17           latencies.
  18
  19 config PREEMPT_VOLUNTARY
  20         bool "Voluntary Kernel Preemption (Desktop)"
  21         depends on !ARCH_NO_PREEMPT
  22         help
  23           This option reduces the latency of the kernel by adding more
  24           "explicit preemption points" to the kernel code. These new
  25           preemption points have been selected to reduce the maximum
  26           latency of rescheduling, providing faster application reactions,
  27           at the cost of slightly lower throughput.
  28
  29           This allows reaction to interactive events by allowing a
  30           low priority process to voluntarily preempt itself even if it
  31           is in kernel mode executing a system call. This allows
  32           applications to run more 'smoothly' even when the system is
  33           under load.
  34
  35           Select this if you are building a kernel for a desktop system.
  36
  37 config PREEMPT
  38         bool "Preemptible Kernel (Low-Latency Desktop)"
  39         depends on !ARCH_NO_PREEMPT
  40         select PREEMPT_COUNT
  41         select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK
  42         help
  43           This option reduces the latency of the kernel by making
  44           all kernel code (that is not executing in a critical section)
  45           preemptible.  This allows reaction to interactive events by
  46           permitting a low priority process to be preempted involuntarily
  47           even if it is in kernel mode executing a system call and would
  48           otherwise not be about to reach a natural preemption point.
  49           This allows applications to run more 'smoothly' even when the
  50           system is under load, at the cost of slightly lower throughput
  51           and a slight runtime overhead to kernel code.
  52
  53           Select this if you are building a kernel for a desktop or
  54           embedded system with latency requirements in the milliseconds
  55           range.
  56
  57 endchoice
  58
  59 config PREEMPT_COUNT
  60        bool