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authorJeff Garzik <jgarzik@pretzel.yyz.us>2005-06-26 23:38:58 -0400
committerJeff Garzik <jgarzik@pobox.com>2005-06-26 23:38:58 -0400
commit5696c1944a33b4434a9a1ebb6383b906afd43a10 (patch)
tree16fbe6ba431bcf949ee8645510b0c2fd39b5810f /kernel/Kconfig.preempt
parent66b04a80eea60cabf9d89fd34deb3234a740052f (diff)
parent020f46a39eb7b99a575b9f4d105fce2b142acdf1 (diff)
downloadlwn-5696c1944a33b4434a9a1ebb6383b906afd43a10.tar.gz
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Merge /spare/repo/linux-2.6/
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+
+choice
+ 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 by adding more
+ "explicit preemption points" to the kernel code. These new
+ preemption points have been selected to reduce the maximum
+ 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.
+
+ Select this if you are building a kernel for a desktop system.
+
+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"
+ depends on SMP || PREEMPT
+ default y
+ help
+ This option reduces the latency of the kernel by making the
+ big kernel lock preemptible.
+
+ Say Y here if you are building a kernel for a desktop system.
+ Say N if you are unsure.
+