| 1 | |
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| 2 | choice |
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| 3 | prompt "Preemption Model" |
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| 4 | default PREEMPT_NONE |
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| 5 | |
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| 6 | config PREEMPT_NONE |
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| 7 | bool "No Forced Preemption (Server)" |
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| 8 | help |
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| 9 | This is the traditional Linux preemption model, geared towards |
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| 10 | throughput. It will still provide good latencies most of the |
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| 11 | time, but there are no guarantees and occasional longer delays |
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| 12 | are possible. |
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| 13 | |
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| 14 | Select this option if you are building a kernel for a server or |
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| 15 | scientific/computation system, or if you want to maximize the |
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| 16 | raw processing power of the kernel, irrespective of scheduling |
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| 17 | latencies. |
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| 18 | |
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| 19 | config PREEMPT_VOLUNTARY |
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| 20 | bool "Voluntary Kernel Preemption (Desktop)" |
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| 21 | help |
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| 22 | This option reduces the latency of the kernel by adding more |
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| 23 | "explicit preemption points" to the kernel code. These new |
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| 24 | preemption points have been selected to reduce the maximum |
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| 25 | latency of rescheduling, providing faster application reactions, |
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| 26 | at the cost of slighly lower throughput. |
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| 27 | |
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| 28 | This allows reaction to interactive events by allowing a |
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| 29 | low priority process to voluntarily preempt itself even if it |
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| 30 | is in kernel mode executing a system call. This allows |
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| 31 | applications to run more 'smoothly' even when the system is |
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| 32 | under load. |
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| 33 | |
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| 34 | Select this if you are building a kernel for a desktop system. |
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| 35 | |
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| 36 | config PREEMPT |
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| 37 | bool "Preemptible Kernel (Low-Latency Desktop)" |
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| 38 | depends on !XEN |
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| 39 | help |
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| 40 | This option reduces the latency of the kernel by making |
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| 41 | all kernel code (that is not executing in a critical section) |
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| 42 | preemptible. This allows reaction to interactive events by |
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| 43 | permitting a low priority process to be preempted involuntarily |
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| 44 | even if it is in kernel mode executing a system call and would |
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| 45 | otherwise not be about to reach a natural preemption point. |
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| 46 | This allows applications to run more 'smoothly' even when the |
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| 47 | system is under load, at the cost of slighly lower throughput |
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| 48 | and a slight runtime overhead to kernel code. |
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| 49 | |
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| 50 | Select this if you are building a kernel for a desktop or |
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| 51 | embedded system with latency requirements in the milliseconds |
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| 52 | range. |
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| 53 | |
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| 54 | endchoice |
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| 55 | |
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| 56 | config PREEMPT_BKL |
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| 57 | bool "Preempt The Big Kernel Lock" |
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| 58 | depends on SMP || PREEMPT |
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| 59 | default y |
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| 60 | help |
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| 61 | This option reduces the latency of the kernel by making the |
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| 62 | big kernel lock preemptible. |
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| 63 | |
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| 64 | Say Y here if you are building a kernel for a desktop system. |
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| 65 | Say N if you are unsure. |
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| 66 | |
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