1 files changed, 49 insertions, 8 deletions
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 34c631221aa3..0b46a5dff4c0 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -1,15 +1,56 @@
-config PREEMPT
+choice
-        bool "Preemptible Kernel"
+        prompt "Preemption Model"
+        default PREEMPT_NONE
+config PREEMPT_NONE
+        bool "No Forced Preemption (Server)"
+        help
+          This is the traditional Linux preemption model, geared towards
+          throughput. It will still provide good latencies most of the
+          time, but there are no guarantees and occasional longer delays
+          are possible.
+          Select this option if you are building a kernel for a server or
+          scientific/computation system, or if you want to maximize the
+          raw processing power of the kernel, irrespective of scheduling
+          latencies.
+config PREEMPT_VOLUNTARY
+        bool "Voluntary Kernel Preemption (Desktop)"
        help
-          This option reduces the latency of the kernel when reacting to
+          This option reduces the latency of the kernel by adding more
-          real-time or interactive events by allowing a low priority process to
+          "explicit preemption points" to the kernel code. These new
-          be preempted even if it is in kernel mode executing a system call.
+          preemption points have been selected to reduce the maximum
-          This allows applications to run more reliably even when the system is
+          latency of rescheduling, providing faster application reactions,
+          at the cost of slighly lower throughput.
+          This allows reaction to interactive events by allowing a
+          low priority process to voluntarily preempt itself even if it
+          is in kernel mode executing a system call. This allows
+          applications to run more 'smoothly' even when the system is
          under load.
-          Say Y here if you are building a kernel for a desktop, embedded
+          Select this if you are building a kernel for a desktop system.
-          or real-time system.  Say N if you are unsure.
+config PREEMPT
+        bool "Preemptible Kernel (Low-Latency Desktop)"
+        help
+          This option reduces the latency of the kernel by making
+          all kernel code (that is not executing in a critical section)
+          preemptible.  This allows reaction to interactive events by
+          permitting a low priority process to be preempted involuntarily
+          even if it is in kernel mode executing a system call and would
+          otherwise not be about to reach a natural preemption point.
+          This allows applications to run more 'smoothly' even when the
+          system is under load, at the cost of slighly lower throughput
+          and a slight runtime overhead to kernel code.
+          Select this if you are building a kernel for a desktop or
+          embedded system with latency requirements in the milliseconds
+          range.
+endchoice
 config PREEMPT_BKL
        bool "Preempt The Big Kernel Lock"

diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt index 34c631221aa3..0b46a5dff4c0 100644 --- a/kernel/Kconfig.preempt +++ b/kernel/Kconfig.preempt
@@ -1,15 +1,56 @@
1		1
2	config PREEMPT	2	choice
3	bool "Preemptible Kernel"	3	prompt "Preemption Model"
		4	default PREEMPT_NONE
		5
		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.
		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
		19	config PREEMPT_VOLUNTARY
		20	bool "Voluntary Kernel Preemption (Desktop)"
4	help	21	help
5	This option reduces the latency of the kernel when reacting to	22	This option reduces the latency of the kernel by adding more
6	real-time or interactive events by allowing a low priority process to	23	"explicit preemption points" to the kernel code. These new
7	be preempted even if it is in kernel mode executing a system call.	24	preemption points have been selected to reduce the maximum
8	This allows applications to run more reliably even when the system is	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
9	under load.	32	under load.
10		33
11	Say Y here if you are building a kernel for a desktop, embedded	34	Select this if you are building a kernel for a desktop system.
12	or real-time system. Say N if you are unsure.	35
		36	config 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 slighly 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
		53	endchoice
13		54
14	config PREEMPT_BKL	55	config PREEMPT_BKL
15	bool "Preempt The Big Kernel Lock"	56	bool "Preempt The Big Kernel Lock"