LXR linux/kernel/Kconfig.preempt

   1
   2choice
   3        prompt "Preemption Model"
   4        default PREEMPT_NONE
   5
   6config 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
  19config PREEMPT_VOLUNTARY
  20        bool "Voluntary Kernel Preemption (Desktop)"
  21        help
  22          This option reduces the latency of the kernel by adding more
  23          "explicit preemption points" to the kernel code. These new
  24          preemption points have been selected to reduce the maximum
  25          latency of rescheduling, providing faster application reactions,
  26          at the cost of slightly lower throughput.
  27
  28          This allows reaction to interactive events by allowing a
  29          low priority process to voluntarily preempt itself even if it
  30          is in kernel mode executing a system call. This allows
  31          applications to run more 'smoothly' even when the system is
  32          under load.
  33
  34          Select this if you are building a kernel for a desktop system.
  35
  36config PREEMPT
  37        bool "Preemptible Kernel (Low-Latency Desktop)"
  38        help
  39          This option reduces the latency of the kernel by making
  40          all kernel code (that is not executing in a critical section)
  41          preemptible.  This allows reaction to interactive events by
  42          permitting a low priority process to be preempted involuntarily
  43          even if it is in kernel mode executing a system call and would
  44          otherwise not be about to reach a natural preemption point.
  45          This allows applications to run more 'smoothly' even when the
  46          system is under load, at the cost of slightly lower throughput
  47          and a slight runtime overhead to kernel code.
  48
  49          Select this if you are building a kernel for a desktop or
  50          embedded system with latency requirements in the milliseconds
  51          range.
  52
  53endchoice
  54
  55config PREEMPT_BKL
  56        bool "Preempt The Big Kernel Lock"
  57        depends on SMP || PREEMPT
  58        default y
  59        help
  60          This option reduces the latency of the kernel by making the
  61          big kernel lock preemptible.
  62
  63          Say Y here if you are building a kernel for a desktop system.
  64          Say N if you are unsure.
  65
  66