kthread: rename probe_kthread_data() to kthread_probe_data()
[linux-2.6-block.git] / kernel / Kconfig.preempt
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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)"
cc19ca86 21 help
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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,
3dde6ad8 26 at the cost of slightly lower throughput.
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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
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32 under load.
33
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34 Select this if you are building a kernel for a desktop system.
35
36config PREEMPT
37 bool "Preemptible Kernel (Low-Latency Desktop)"
bdd4e85d 38 select PREEMPT_COUNT
e335e3eb 39 select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK
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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
3dde6ad8 48 system is under load, at the cost of slightly lower throughput
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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
cc19ca86 56
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57config PREEMPT_COUNT
58 bool