Kconfig.preempt (71af75b6929458d85f63c0649dc26d6f4c19729e) | Kconfig.preempt (c597bfddc9e9e8a63817252b67c3ca0e544ace26) |
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1# SPDX-License-Identifier: GPL-2.0-only 2 3choice 4 prompt "Preemption Model" | 1# SPDX-License-Identifier: GPL-2.0-only 2 3choice 4 prompt "Preemption Model" |
5 default PREEMPT_NONE | 5 default PREEMPT_NONE_BEHAVIOUR |
6 | 6 |
7config PREEMPT_NONE | 7config PREEMPT_NONE_BEHAVIOUR |
8 bool "No Forced Preemption (Server)" | 8 bool "No Forced Preemption (Server)" |
9 select PREEMPT_NONE if !PREEMPT_DYNAMIC |
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9 help 10 This is the traditional Linux preemption model, geared towards 11 throughput. It will still provide good latencies most of the 12 time, but there are no guarantees and occasional longer delays 13 are possible. 14 15 Select this option if you are building a kernel for a server or 16 scientific/computation system, or if you want to maximize the 17 raw processing power of the kernel, irrespective of scheduling 18 latencies. 19 | 10 help 11 This is the traditional Linux preemption model, geared towards 12 throughput. It will still provide good latencies most of the 13 time, but there are no guarantees and occasional longer delays 14 are possible. 15 16 Select this option if you are building a kernel for a server or 17 scientific/computation system, or if you want to maximize the 18 raw processing power of the kernel, irrespective of scheduling 19 latencies. 20 |
20config PREEMPT_VOLUNTARY | 21config PREEMPT_VOLUNTARY_BEHAVIOUR |
21 bool "Voluntary Kernel Preemption (Desktop)" 22 depends on !ARCH_NO_PREEMPT | 22 bool "Voluntary Kernel Preemption (Desktop)" 23 depends on !ARCH_NO_PREEMPT |
24 select PREEMPT_VOLUNTARY if !PREEMPT_DYNAMIC |
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23 help 24 This option reduces the latency of the kernel by adding more 25 "explicit preemption points" to the kernel code. These new 26 preemption points have been selected to reduce the maximum 27 latency of rescheduling, providing faster application reactions, 28 at the cost of slightly lower throughput. 29 30 This allows reaction to interactive events by allowing a 31 low priority process to voluntarily preempt itself even if it 32 is in kernel mode executing a system call. This allows 33 applications to run more 'smoothly' even when the system is 34 under load. 35 36 Select this if you are building a kernel for a desktop system. 37 | 25 help 26 This option reduces the latency of the kernel by adding more 27 "explicit preemption points" to the kernel code. These new 28 preemption points have been selected to reduce the maximum 29 latency of rescheduling, providing faster application reactions, 30 at the cost of slightly lower throughput. 31 32 This allows reaction to interactive events by allowing a 33 low priority process to voluntarily preempt itself even if it 34 is in kernel mode executing a system call. This allows 35 applications to run more 'smoothly' even when the system is 36 under load. 37 38 Select this if you are building a kernel for a desktop system. 39 |
38config PREEMPT | 40config PREEMPT_BEHAVIOUR |
39 bool "Preemptible Kernel (Low-Latency Desktop)" 40 depends on !ARCH_NO_PREEMPT | 41 bool "Preemptible Kernel (Low-Latency Desktop)" 42 depends on !ARCH_NO_PREEMPT |
41 select PREEMPTION 42 select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK 43 select PREEMPT_DYNAMIC if HAVE_PREEMPT_DYNAMIC | 43 select PREEMPT |
44 help 45 This option reduces the latency of the kernel by making 46 all kernel code (that is not executing in a critical section) 47 preemptible. This allows reaction to interactive events by 48 permitting a low priority process to be preempted involuntarily 49 even if it is in kernel mode executing a system call and would 50 otherwise not be about to reach a natural preemption point. 51 This allows applications to run more 'smoothly' even when the 52 system is under load, at the cost of slightly lower throughput 53 and a slight runtime overhead to kernel code. 54 55 Select this if you are building a kernel for a desktop or 56 embedded system with latency requirements in the milliseconds 57 range. 58 59config PREEMPT_RT 60 bool "Fully Preemptible Kernel (Real-Time)" | 44 help 45 This option reduces the latency of the kernel by making 46 all kernel code (that is not executing in a critical section) 47 preemptible. This allows reaction to interactive events by 48 permitting a low priority process to be preempted involuntarily 49 even if it is in kernel mode executing a system call and would 50 otherwise not be about to reach a natural preemption point. 51 This allows applications to run more 'smoothly' even when the 52 system is under load, at the cost of slightly lower throughput 53 and a slight runtime overhead to kernel code. 54 55 Select this if you are building a kernel for a desktop or 56 embedded system with latency requirements in the milliseconds 57 range. 58 59config PREEMPT_RT 60 bool "Fully Preemptible Kernel (Real-Time)" |
61 depends on EXPERT && ARCH_SUPPORTS_RT | 61 depends on EXPERT && ARCH_SUPPORTS_RT && !PREEMPT_DYNAMIC |
62 select PREEMPTION 63 help 64 This option turns the kernel into a real-time kernel by replacing 65 various locking primitives (spinlocks, rwlocks, etc.) with 66 preemptible priority-inheritance aware variants, enforcing 67 interrupt threading and introducing mechanisms to break up long 68 non-preemptible sections. This makes the kernel, except for very 69 low level and critical code paths (entry code, scheduler, low 70 level interrupt handling) fully preemptible and brings most 71 execution contexts under scheduler control. 72 73 Select this if you are building a kernel for systems which 74 require real-time guarantees. 75 76endchoice 77 | 62 select PREEMPTION 63 help 64 This option turns the kernel into a real-time kernel by replacing 65 various locking primitives (spinlocks, rwlocks, etc.) with 66 preemptible priority-inheritance aware variants, enforcing 67 interrupt threading and introducing mechanisms to break up long 68 non-preemptible sections. This makes the kernel, except for very 69 low level and critical code paths (entry code, scheduler, low 70 level interrupt handling) fully preemptible and brings most 71 execution contexts under scheduler control. 72 73 Select this if you are building a kernel for systems which 74 require real-time guarantees. 75 76endchoice 77 |
78config PREEMPT_NONE 79 bool 80 81config PREEMPT_VOLUNTARY 82 bool 83 84config PREEMPT 85 bool 86 select PREEMPTION 87 select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK 88 |
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78config PREEMPT_COUNT 79 bool 80 81config PREEMPTION 82 bool 83 select PREEMPT_COUNT 84 85config PREEMPT_DYNAMIC | 89config PREEMPT_COUNT 90 bool 91 92config PREEMPTION 93 bool 94 select PREEMPT_COUNT 95 96config PREEMPT_DYNAMIC |
86 bool | 97 bool "Preemption behaviour defined on boot" 98 depends on HAVE_PREEMPT_DYNAMIC 99 select PREEMPT 100 default y |
87 help 88 This option allows to define the preemption model on the kernel 89 command line parameter and thus override the default preemption 90 model defined during compile time. 91 92 The feature is primarily interesting for Linux distributions which 93 provide a pre-built kernel binary to reduce the number of kernel 94 flavors they offer while still offering different usecases. --- 27 unchanged lines hidden --- | 101 help 102 This option allows to define the preemption model on the kernel 103 command line parameter and thus override the default preemption 104 model defined during compile time. 105 106 The feature is primarily interesting for Linux distributions which 107 provide a pre-built kernel binary to reduce the number of kernel 108 flavors they offer while still offering different usecases. --- 27 unchanged lines hidden --- |