ia64/linux-2.6.18-xen.hg

view kernel/Kconfig.preempt @ 562:66faefe721eb

pvSCSI backend driver

Signed-off-by: Tomonari Horikoshi <t.horikoshi@jp.fujitsu.com>
Signed-off-by: Jun Kamada <kama@jp.fujitsu.com>
author Keir Fraser <keir.fraser@citrix.com>
date Mon Jun 02 09:58:27 2008 +0100 (2008-06-02)
parents a533be77c572
children
line source
2 choice
3 prompt "Preemption Model"
4 default PREEMPT_NONE
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.
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.
19 config 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.
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.
34 Select this if you are building a kernel for a desktop system.
36 config 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.
50 Select this if you are building a kernel for a desktop or
51 embedded system with latency requirements in the milliseconds
52 range.
54 endchoice
56 config 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.
64 Say Y here if you are building a kernel for a desktop system.
65 Say N if you are unsure.