source: trunk/packages/xen-3.1/xen-3.1/linux-2.6-xen-sparse/kernel/Kconfig.preempt @ 34

Last change on this file since 34 was 34, checked in by hartmans, 18 years ago

Add xen and xen-common

File size: 2.3 KB
Line 
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 slighly 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        depends on !XEN
39        help
40          This option reduces the latency of the kernel by making
41          all kernel code (that is not executing in a critical section)
42          preemptible.  This allows reaction to interactive events by
43          permitting a low priority process to be preempted involuntarily
44          even if it is in kernel mode executing a system call and would
45          otherwise not be about to reach a natural preemption point.
46          This allows applications to run more 'smoothly' even when the
47          system is under load, at the cost of slighly lower throughput
48          and a slight runtime overhead to kernel code.
49
50          Select this if you are building a kernel for a desktop or
51          embedded system with latency requirements in the milliseconds
52          range.
53
54endchoice
55
56config PREEMPT_BKL
57        bool "Preempt The Big Kernel Lock"
58        depends on SMP || PREEMPT
59        default y
60        help
61          This option reduces the latency of the kernel by making the
62          big kernel lock preemptible.
63
64          Say Y here if you are building a kernel for a desktop system.
65          Say N if you are unsure.
66
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