xref: /openbmc/linux/kernel/Kconfig.preempt (revision ba61bb17)
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	select PREEMPT_COUNT
39	select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK
40	help
41	  This option reduces the latency of the kernel by making
42	  all kernel code (that is not executing in a critical section)
43	  preemptible.  This allows reaction to interactive events by
44	  permitting a low priority process to be preempted involuntarily
45	  even if it is in kernel mode executing a system call and would
46	  otherwise not be about to reach a natural preemption point.
47	  This allows applications to run more 'smoothly' even when the
48	  system is under load, at the cost of slightly lower throughput
49	  and a slight runtime overhead to kernel code.
50
51	  Select this if you are building a kernel for a desktop or
52	  embedded system with latency requirements in the milliseconds
53	  range.
54
55endchoice
56
57config PREEMPT_COUNT
58       bool