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TOMOYO Linux Cross Reference
Linux/kernel/time/Kconfig

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Differences between /kernel/time/Kconfig (Architecture i386) and /kernel/time/Kconfig (Architecture m68k)


  1 # SPDX-License-Identifier: GPL-2.0-only             1 # SPDX-License-Identifier: GPL-2.0-only
  2 #                                                   2 #
  3 # Timer subsystem related configuration option      3 # Timer subsystem related configuration options
  4 #                                                   4 #
  5                                                     5 
  6 # Options selectable by arch Kconfig                6 # Options selectable by arch Kconfig
  7                                                     7 
  8 # Watchdog function for clocksources to detect      8 # Watchdog function for clocksources to detect instabilities
  9 config CLOCKSOURCE_WATCHDOG                         9 config CLOCKSOURCE_WATCHDOG
 10         bool                                       10         bool
 11                                                    11 
 12 # Architecture has extra clocksource data          12 # Architecture has extra clocksource data
 13 config ARCH_CLOCKSOURCE_DATA                       13 config ARCH_CLOCKSOURCE_DATA
 14         bool                                       14         bool
 15                                                    15 
 16 # Architecture has extra clocksource init call     16 # Architecture has extra clocksource init called from registration
 17 config ARCH_CLOCKSOURCE_INIT                       17 config ARCH_CLOCKSOURCE_INIT
 18         bool                                       18         bool
 19                                                    19 
 20 # Clocksources require validation of the clock     20 # Clocksources require validation of the clocksource against the last
 21 # cycle update - x86/TSC misfeature                21 # cycle update - x86/TSC misfeature
 22 config CLOCKSOURCE_VALIDATE_LAST_CYCLE             22 config CLOCKSOURCE_VALIDATE_LAST_CYCLE
 23         bool                                       23         bool
 24                                                    24 
 25 # Timekeeping vsyscall support                     25 # Timekeeping vsyscall support
 26 config GENERIC_TIME_VSYSCALL                       26 config GENERIC_TIME_VSYSCALL
 27         bool                                       27         bool
 28                                                    28 
 29 # The generic clock events infrastructure          29 # The generic clock events infrastructure
 30 config GENERIC_CLOCKEVENTS                         30 config GENERIC_CLOCKEVENTS
 31         def_bool !LEGACY_TIMER_TICK                31         def_bool !LEGACY_TIMER_TICK
 32                                                    32 
 33 # Architecture can handle broadcast in a drive     33 # Architecture can handle broadcast in a driver-agnostic way
 34 config ARCH_HAS_TICK_BROADCAST                     34 config ARCH_HAS_TICK_BROADCAST
 35         bool                                       35         bool
 36                                                    36 
 37 # Clockevents broadcasting infrastructure          37 # Clockevents broadcasting infrastructure
 38 config GENERIC_CLOCKEVENTS_BROADCAST               38 config GENERIC_CLOCKEVENTS_BROADCAST
 39         bool                                       39         bool
 40         depends on GENERIC_CLOCKEVENTS             40         depends on GENERIC_CLOCKEVENTS
 41                                                    41 
 42 # Handle broadcast in default_idle_call()          42 # Handle broadcast in default_idle_call()
 43 config GENERIC_CLOCKEVENTS_BROADCAST_IDLE          43 config GENERIC_CLOCKEVENTS_BROADCAST_IDLE
 44         bool                                       44         bool
 45         depends on GENERIC_CLOCKEVENTS_BROADCA     45         depends on GENERIC_CLOCKEVENTS_BROADCAST
 46                                                    46 
 47 # Automatically adjust the min. reprogramming      47 # Automatically adjust the min. reprogramming time for
 48 # clock event device                               48 # clock event device
 49 config GENERIC_CLOCKEVENTS_MIN_ADJUST              49 config GENERIC_CLOCKEVENTS_MIN_ADJUST
 50         bool                                       50         bool
 51                                                    51 
 52 # Generic update of CMOS clock                     52 # Generic update of CMOS clock
 53 config GENERIC_CMOS_UPDATE                         53 config GENERIC_CMOS_UPDATE
 54         bool                                       54         bool
 55                                                    55 
 56 # Select to handle posix CPU timers from task_     56 # Select to handle posix CPU timers from task_work
 57 # and not from the timer interrupt context         57 # and not from the timer interrupt context
 58 config HAVE_POSIX_CPU_TIMERS_TASK_WORK             58 config HAVE_POSIX_CPU_TIMERS_TASK_WORK
 59         bool                                       59         bool
 60                                                    60 
 61 config POSIX_CPU_TIMERS_TASK_WORK                  61 config POSIX_CPU_TIMERS_TASK_WORK
 62         bool                                       62         bool
 63         default y if POSIX_TIMERS && HAVE_POSI     63         default y if POSIX_TIMERS && HAVE_POSIX_CPU_TIMERS_TASK_WORK
 64                                                    64 
 65 config LEGACY_TIMER_TICK                           65 config LEGACY_TIMER_TICK
 66         bool                                       66         bool
 67         help                                       67         help
 68           The legacy timer tick helper is used     68           The legacy timer tick helper is used by platforms that
 69           lack support for the generic clockev     69           lack support for the generic clockevent framework.
 70           New platforms should use generic clo     70           New platforms should use generic clockevents instead.
 71                                                    71 
 72 config TIME_KUNIT_TEST                             72 config TIME_KUNIT_TEST
 73         tristate "KUnit test for kernel/time f     73         tristate "KUnit test for kernel/time functions" if !KUNIT_ALL_TESTS
 74         depends on KUNIT                           74         depends on KUNIT
 75         default KUNIT_ALL_TESTS                    75         default KUNIT_ALL_TESTS
 76         help                                       76         help
 77           Enable this option to test RTC libra     77           Enable this option to test RTC library functions.
 78                                                    78 
 79           If unsure, say N.                        79           If unsure, say N.
 80                                                    80 
 81 config CONTEXT_TRACKING                            81 config CONTEXT_TRACKING
 82         bool                                       82         bool
 83                                                    83 
 84 config CONTEXT_TRACKING_IDLE                       84 config CONTEXT_TRACKING_IDLE
 85         bool                                       85         bool
 86         select CONTEXT_TRACKING                    86         select CONTEXT_TRACKING
 87         help                                       87         help
 88           Tracks idle state on behalf of RCU.      88           Tracks idle state on behalf of RCU.
 89                                                    89 
 90 if GENERIC_CLOCKEVENTS                             90 if GENERIC_CLOCKEVENTS
 91 menu "Timers subsystem"                            91 menu "Timers subsystem"
 92                                                    92 
 93 # Core internal switch. Selected by NO_HZ_COMM     93 # Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
 94 # only related to the tick functionality. Ones     94 # only related to the tick functionality. Oneshot clockevent devices
 95 # are supported independent of this.               95 # are supported independent of this.
 96 config TICK_ONESHOT                                96 config TICK_ONESHOT
 97         bool                                       97         bool
 98                                                    98 
 99 config NO_HZ_COMMON                                99 config NO_HZ_COMMON
100         bool                                      100         bool
101         select TICK_ONESHOT                       101         select TICK_ONESHOT
102                                                   102 
103 choice                                            103 choice
104         prompt "Timer tick handling"              104         prompt "Timer tick handling"
105         default NO_HZ_IDLE if NO_HZ               105         default NO_HZ_IDLE if NO_HZ
106                                                   106 
107 config HZ_PERIODIC                                107 config HZ_PERIODIC
108         bool "Periodic timer ticks (constant r    108         bool "Periodic timer ticks (constant rate, no dynticks)"
109         help                                      109         help
110           This option keeps the tick running p    110           This option keeps the tick running periodically at a constant
111           rate, even when the CPU doesn't need    111           rate, even when the CPU doesn't need it.
112                                                   112 
113 config NO_HZ_IDLE                                 113 config NO_HZ_IDLE
114         bool "Idle dynticks system (tickless i    114         bool "Idle dynticks system (tickless idle)"
115         select NO_HZ_COMMON                       115         select NO_HZ_COMMON
116         help                                      116         help
117           This option enables a tickless idle     117           This option enables a tickless idle system: timer interrupts
118           will only trigger on an as-needed ba    118           will only trigger on an as-needed basis when the system is idle.
119           This is usually interesting for ener    119           This is usually interesting for energy saving.
120                                                   120 
121           Most of the time you want to say Y h    121           Most of the time you want to say Y here.
122                                                   122 
123 config NO_HZ_FULL                                 123 config NO_HZ_FULL
124         bool "Full dynticks system (tickless)"    124         bool "Full dynticks system (tickless)"
125         # NO_HZ_COMMON dependency                 125         # NO_HZ_COMMON dependency
126         # We need at least one periodic CPU fo    126         # We need at least one periodic CPU for timekeeping
127         depends on SMP                            127         depends on SMP
128         depends on HAVE_CONTEXT_TRACKING_USER     128         depends on HAVE_CONTEXT_TRACKING_USER
129         # VIRT_CPU_ACCOUNTING_GEN dependency      129         # VIRT_CPU_ACCOUNTING_GEN dependency
130         depends on HAVE_VIRT_CPU_ACCOUNTING_GE    130         depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
131         select NO_HZ_COMMON                       131         select NO_HZ_COMMON
132         select RCU_NOCB_CPU                       132         select RCU_NOCB_CPU
133         select VIRT_CPU_ACCOUNTING_GEN            133         select VIRT_CPU_ACCOUNTING_GEN
134         select IRQ_WORK                           134         select IRQ_WORK
135         select CPU_ISOLATION                      135         select CPU_ISOLATION
136         help                                      136         help
137          Adaptively try to shutdown the tick w    137          Adaptively try to shutdown the tick whenever possible, even when
138          the CPU is running tasks. Typically t    138          the CPU is running tasks. Typically this requires running a single
139          task on the CPU. Chances for running     139          task on the CPU. Chances for running tickless are maximized when
140          the task mostly runs in userspace and    140          the task mostly runs in userspace and has few kernel activity.
141                                                   141 
142          You need to fill up the nohz_full boo    142          You need to fill up the nohz_full boot parameter with the
143          desired range of dynticks CPUs to use    143          desired range of dynticks CPUs to use it. This is implemented at
144          the expense of some overhead in user     144          the expense of some overhead in user <-> kernel transitions:
145          syscalls, exceptions and interrupts.     145          syscalls, exceptions and interrupts.
146                                                   146 
147          By default, without passing the nohz_    147          By default, without passing the nohz_full parameter, this behaves just
148          like NO_HZ_IDLE.                         148          like NO_HZ_IDLE.
149                                                   149 
150          If you're a distro say Y.                150          If you're a distro say Y.
151                                                   151 
152 endchoice                                         152 endchoice
153                                                   153 
154 config CONTEXT_TRACKING_USER                      154 config CONTEXT_TRACKING_USER
155         bool                                      155         bool
156         depends on HAVE_CONTEXT_TRACKING_USER     156         depends on HAVE_CONTEXT_TRACKING_USER
157         select CONTEXT_TRACKING                   157         select CONTEXT_TRACKING
158         help                                      158         help
159           Track transitions between kernel and    159           Track transitions between kernel and user on behalf of RCU and
160           tickless cputime accounting. The for    160           tickless cputime accounting. The former case relies on context
161           tracking to enter/exit RCU extended     161           tracking to enter/exit RCU extended quiescent states.
162                                                   162 
163 config CONTEXT_TRACKING_USER_FORCE                163 config CONTEXT_TRACKING_USER_FORCE
164         bool "Force user context tracking"        164         bool "Force user context tracking"
165         depends on CONTEXT_TRACKING_USER          165         depends on CONTEXT_TRACKING_USER
166         default y if !NO_HZ_FULL                  166         default y if !NO_HZ_FULL
167         help                                      167         help
168           The major pre-requirement for full d    168           The major pre-requirement for full dynticks to work is to
169           support the user context tracking su    169           support the user context tracking subsystem. But there are also
170           other dependencies to provide in ord    170           other dependencies to provide in order to make the full
171           dynticks working.                       171           dynticks working.
172                                                   172 
173           This option stands for testing when     173           This option stands for testing when an arch implements the
174           user context tracking backend but do    174           user context tracking backend but doesn't yet fulfill all the
175           requirements to make the full dyntic    175           requirements to make the full dynticks feature working.
176           Without the full dynticks, there is     176           Without the full dynticks, there is no way to test the support
177           for user context tracking and the su    177           for user context tracking and the subsystems that rely on it: RCU
178           userspace extended quiescent state a    178           userspace extended quiescent state and tickless cputime
179           accounting. This option copes with t    179           accounting. This option copes with the absence of the full
180           dynticks subsystem by forcing the us    180           dynticks subsystem by forcing the user context tracking on all
181           CPUs in the system.                     181           CPUs in the system.
182                                                   182 
183           Say Y only if you're working on the     183           Say Y only if you're working on the development of an
184           architecture backend for the user co    184           architecture backend for the user context tracking.
185                                                   185 
186           Say N otherwise, this option brings     186           Say N otherwise, this option brings an overhead that you
187           don't want in production.               187           don't want in production.
188                                                   188 
189 config NO_HZ                                      189 config NO_HZ
190         bool "Old Idle dynticks config"           190         bool "Old Idle dynticks config"
191         help                                      191         help
192           This is the old config entry that en    192           This is the old config entry that enables dynticks idle.
193           We keep it around for a little while    193           We keep it around for a little while to enforce backward
194           compatibility with older config file    194           compatibility with older config files.
195                                                   195 
196 config HIGH_RES_TIMERS                            196 config HIGH_RES_TIMERS
197         bool "High Resolution Timer Support"      197         bool "High Resolution Timer Support"
198         select TICK_ONESHOT                       198         select TICK_ONESHOT
199         help                                      199         help
200           This option enables high resolution     200           This option enables high resolution timer support. If your
201           hardware is not capable then this op    201           hardware is not capable then this option only increases
202           the size of the kernel image.           202           the size of the kernel image.
203                                                   203 
204 config CLOCKSOURCE_WATCHDOG_MAX_SKEW_US           204 config CLOCKSOURCE_WATCHDOG_MAX_SKEW_US
205         int "Clocksource watchdog maximum allo    205         int "Clocksource watchdog maximum allowable skew (in microseconds)"
206         depends on CLOCKSOURCE_WATCHDOG           206         depends on CLOCKSOURCE_WATCHDOG
207         range 50 1000                             207         range 50 1000
208         default 125                               208         default 125
209         help                                      209         help
210           Specify the maximum amount of allowa    210           Specify the maximum amount of allowable watchdog skew in
211           microseconds before reporting the cl    211           microseconds before reporting the clocksource to be unstable.
212           The default is based on a half-secon    212           The default is based on a half-second clocksource watchdog
213           interval and NTP's maximum frequency    213           interval and NTP's maximum frequency drift of 500 parts
214           per million.  If the clocksource is     214           per million.  If the clocksource is good enough for NTP,
215           it is good enough for the clocksourc    215           it is good enough for the clocksource watchdog!
216                                                   216 
217 endmenu                                           217 endmenu
218 endif                                             218 endif
                                                      

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