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Linux/kernel/Kconfig.preempt

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Diff markup

Differences between /kernel/Kconfig.preempt (Version linux-6.12-rc7) and /kernel/Kconfig.preempt (Version linux-4.18.20)


  1 # SPDX-License-Identifier: GPL-2.0-only        << 
  2                                                << 
  3 config PREEMPT_NONE_BUILD                      << 
  4         bool                                   << 
  5                                                << 
  6 config PREEMPT_VOLUNTARY_BUILD                 << 
  7         bool                                   << 
  8                                                << 
  9 config PREEMPT_BUILD                           << 
 10         bool                                   << 
 11         select PREEMPTION                      << 
 12         select UNINLINE_SPIN_UNLOCK if !ARCH_I << 
 13                                                     1 
 14 choice                                              2 choice
 15         prompt "Preemption Model"                   3         prompt "Preemption Model"
 16         default PREEMPT_NONE                        4         default PREEMPT_NONE
 17                                                     5 
 18 config PREEMPT_NONE                                 6 config PREEMPT_NONE
 19         bool "No Forced Preemption (Server)"        7         bool "No Forced Preemption (Server)"
 20         select PREEMPT_NONE_BUILD if !PREEMPT_ << 
 21         help                                        8         help
 22           This is the traditional Linux preemp      9           This is the traditional Linux preemption model, geared towards
 23           throughput. It will still provide go     10           throughput. It will still provide good latencies most of the
 24           time, but there are no guarantees an     11           time, but there are no guarantees and occasional longer delays
 25           are possible.                            12           are possible.
 26                                                    13 
 27           Select this option if you are buildi     14           Select this option if you are building a kernel for a server or
 28           scientific/computation system, or if     15           scientific/computation system, or if you want to maximize the
 29           raw processing power of the kernel,      16           raw processing power of the kernel, irrespective of scheduling
 30           latencies.                               17           latencies.
 31                                                    18 
 32 config PREEMPT_VOLUNTARY                           19 config PREEMPT_VOLUNTARY
 33         bool "Voluntary Kernel Preemption (Des     20         bool "Voluntary Kernel Preemption (Desktop)"
 34         depends on !ARCH_NO_PREEMPT            << 
 35         select PREEMPT_VOLUNTARY_BUILD if !PRE << 
 36         help                                       21         help
 37           This option reduces the latency of t     22           This option reduces the latency of the kernel by adding more
 38           "explicit preemption points" to the      23           "explicit preemption points" to the kernel code. These new
 39           preemption points have been selected     24           preemption points have been selected to reduce the maximum
 40           latency of rescheduling, providing f     25           latency of rescheduling, providing faster application reactions,
 41           at the cost of slightly lower throug     26           at the cost of slightly lower throughput.
 42                                                    27 
 43           This allows reaction to interactive      28           This allows reaction to interactive events by allowing a
 44           low priority process to voluntarily      29           low priority process to voluntarily preempt itself even if it
 45           is in kernel mode executing a system     30           is in kernel mode executing a system call. This allows
 46           applications to run more 'smoothly'      31           applications to run more 'smoothly' even when the system is
 47           under load.                              32           under load.
 48                                                    33 
 49           Select this if you are building a ke     34           Select this if you are building a kernel for a desktop system.
 50                                                    35 
 51 config PREEMPT                                     36 config PREEMPT
 52         bool "Preemptible Kernel (Low-Latency      37         bool "Preemptible Kernel (Low-Latency Desktop)"
 53         depends on !ARCH_NO_PREEMPT            !!  38         select PREEMPT_COUNT
 54         select PREEMPT_BUILD                   !!  39         select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK
 55         help                                       40         help
 56           This option reduces the latency of t     41           This option reduces the latency of the kernel by making
 57           all kernel code (that is not executi     42           all kernel code (that is not executing in a critical section)
 58           preemptible.  This allows reaction t     43           preemptible.  This allows reaction to interactive events by
 59           permitting a low priority process to     44           permitting a low priority process to be preempted involuntarily
 60           even if it is in kernel mode executi     45           even if it is in kernel mode executing a system call and would
 61           otherwise not be about to reach a na     46           otherwise not be about to reach a natural preemption point.
 62           This allows applications to run more     47           This allows applications to run more 'smoothly' even when the
 63           system is under load, at the cost of     48           system is under load, at the cost of slightly lower throughput
 64           and a slight runtime overhead to ker     49           and a slight runtime overhead to kernel code.
 65                                                    50 
 66           Select this if you are building a ke     51           Select this if you are building a kernel for a desktop or
 67           embedded system with latency require     52           embedded system with latency requirements in the milliseconds
 68           range.                                   53           range.
 69                                                    54 
 70 config PREEMPT_RT                              << 
 71         bool "Fully Preemptible Kernel (Real-T << 
 72         depends on EXPERT && ARCH_SUPPORTS_RT  << 
 73         select PREEMPTION                      << 
 74         help                                   << 
 75           This option turns the kernel into a  << 
 76           various locking primitives (spinlock << 
 77           preemptible priority-inheritance awa << 
 78           interrupt threading and introducing  << 
 79           non-preemptible sections. This makes << 
 80           low level and critical code paths (e << 
 81           level interrupt handling) fully pree << 
 82           execution contexts under scheduler c << 
 83                                                << 
 84           Select this if you are building a ke << 
 85           require real-time guarantees.        << 
 86                                                << 
 87 endchoice                                          55 endchoice
 88                                                    56 
 89 config PREEMPT_COUNT                               57 config PREEMPT_COUNT
 90        bool                                    !!  58        bool
 91                                                << 
 92 config PREEMPTION                              << 
 93        bool                                    << 
 94        select PREEMPT_COUNT                    << 
 95                                                << 
 96 config PREEMPT_DYNAMIC                         << 
 97         bool "Preemption behaviour defined on  << 
 98         depends on HAVE_PREEMPT_DYNAMIC && !PR << 
 99         select JUMP_LABEL if HAVE_PREEMPT_DYNA << 
100         select PREEMPT_BUILD                   << 
101         default y if HAVE_PREEMPT_DYNAMIC_CALL << 
102         help                                   << 
103           This option allows to define the pre << 
104           command line parameter and thus over << 
105           model defined during compile time.   << 
106                                                << 
107           The feature is primarily interesting << 
108           provide a pre-built kernel binary to << 
109           flavors they offer while still offer << 
110                                                << 
111           The runtime overhead is negligible w << 
112           but if runtime patching is not avail << 
113           then the potential overhead should b << 
114                                                << 
115           Interesting if you want the same pre << 
116           both Server and Desktop workloads.   << 
117                                                << 
118 config SCHED_CORE                              << 
119         bool "Core Scheduling for SMT"         << 
120         depends on SCHED_SMT                   << 
121         help                                   << 
122           This option permits Core Scheduling, << 
123           selection across SMT siblings. When  << 
124           prctl(PR_SCHED_CORE) -- task selecti << 
125           will execute a task from the same 'c << 
126           matching task is found.              << 
127                                                << 
128           Use of this feature includes:        << 
129            - mitigation of some (not all) SMT  << 
130            - limiting SMT interference to impr << 
131                                                << 
132           SCHED_CORE is default disabled. When << 
133           which is the likely usage by Linux d << 
134           be no measurable impact on performan << 
135                                                << 
136 config SCHED_CLASS_EXT                         << 
137         bool "Extensible Scheduling Class"     << 
138         depends on BPF_SYSCALL && BPF_JIT && D << 
139         select STACKTRACE if STACKTRACE_SUPPOR << 
140         help                                   << 
141           This option enables a new scheduler  << 
142           allows scheduling policies to be imp << 
143           achieve the following:               << 
144                                                << 
145           - Ease of experimentation and explor << 
146             iteration of new scheduling polici << 
147           - Customization: Building applicatio << 
148             implement policies that are not ap << 
149             schedulers.                        << 
150           - Rapid scheduler deployments: Non-d << 
151             scheduling policies in production  << 
152                                                << 
153           sched_ext leverages BPF struct_ops f << 
154           which exports function callbacks and << 
155           wish to implement scheduling policie << 
156           exported by sched_ext is struct sche << 
157           similar to struct sched_class.       << 
158                                                << 
159           For more information:                << 
160             Documentation/scheduler/sched-ext. << 
161             https://github.com/sched-ext/scx   << 
                                                      

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