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87a4c37599
Almost all architectures include it. Add a ARCH_NO_PREEMPT symbol to disable preempt support for alpha, hexagon, non-coldfire m68k and user mode Linux. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
60 lines
2.2 KiB
Plaintext
60 lines
2.2 KiB
Plaintext
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choice
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prompt "Preemption Model"
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default PREEMPT_NONE
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config PREEMPT_NONE
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bool "No Forced Preemption (Server)"
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help
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This is the traditional Linux preemption model, geared towards
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throughput. It will still provide good latencies most of the
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time, but there are no guarantees and occasional longer delays
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are possible.
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Select this option if you are building a kernel for a server or
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scientific/computation system, or if you want to maximize the
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raw processing power of the kernel, irrespective of scheduling
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latencies.
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config PREEMPT_VOLUNTARY
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bool "Voluntary Kernel Preemption (Desktop)"
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depends on !ARCH_NO_PREEMPT
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help
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This option reduces the latency of the kernel by adding more
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"explicit preemption points" to the kernel code. These new
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preemption points have been selected to reduce the maximum
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latency of rescheduling, providing faster application reactions,
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at the cost of slightly lower throughput.
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This allows reaction to interactive events by allowing a
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low priority process to voluntarily preempt itself even if it
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is in kernel mode executing a system call. This allows
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applications to run more 'smoothly' even when the system is
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under load.
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Select this if you are building a kernel for a desktop system.
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config PREEMPT
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bool "Preemptible Kernel (Low-Latency Desktop)"
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depends on !ARCH_NO_PREEMPT
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select PREEMPT_COUNT
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select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK
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help
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This option reduces the latency of the kernel by making
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all kernel code (that is not executing in a critical section)
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preemptible. This allows reaction to interactive events by
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permitting a low priority process to be preempted involuntarily
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even if it is in kernel mode executing a system call and would
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otherwise not be about to reach a natural preemption point.
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This allows applications to run more 'smoothly' even when the
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system is under load, at the cost of slightly lower throughput
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and a slight runtime overhead to kernel code.
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Select this if you are building a kernel for a desktop or
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embedded system with latency requirements in the milliseconds
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range.
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endchoice
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config PREEMPT_COUNT
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bool |