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[PATCH] tick-management: dyntick / highres functionality With Ingo Molnar <mingo@elte.hu> Add functions to provide dynamic ticks and high resolution timers. The code which keeps track of jiffies and handles the long idle periods is shared between tick based and high resolution timer based dynticks. The dyntick functionality can be disabled on the kernel commandline. Provide also the infrastructure to support high resolution timers. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: john stultz <johnstul@us.ibm.com> Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-16 17:28:03 +08:00
#
# Timer subsystem related configuration options
#
tick: Document TICK_ONESHOT config option This option has been selected from arch code as it was assumed that it's necessary to support oneshot mode clockevent devices. But it's just a core internal helper to compile tick-oneshot.c if NOHZ or HIG_RES_TIMERS are selected. Reported-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-03-31 18:45:43 +08:00
timers: Provide generic Kconfig switches We really don't want all the arch code defining stuff over and over. [ anna-maria: Added missing GENERIC_CMOS_UPDATE switch ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@glx-um.de> Cc: Paul Mundt <lethal@linux-sh.org> Link: http://lkml.kernel.org/r/1337529587.3208.2.camel@dionysos Acked-by: Sam Ravnborg <sam@ravnborg.org>
2012-05-18 15:59:57 +08:00
# Options selectable by arch Kconfig
# Watchdog function for clocksources to detect instabilities
config CLOCKSOURCE_WATCHDOG
bool
# Architecture has extra clocksource data
config ARCH_CLOCKSOURCE_DATA
bool
clocksource: Move cycle_last validation to core code The only user of the cycle_last validation is the x86 TSC. In order to provide NMI safe accessor functions for clock monotonic and monotonic_raw we need to do that in the core. We can't do the TSC specific if (now < cycle_last) now = cycle_last; for the other wrapping around clocksources, but TSC has CLOCKSOURCE_MASK(64) which actually does not mask out anything so if now is less than cycle_last the subtraction will give a negative result. So we can check for that in clocksource_delta() and return 0 for that case. Implement and enable it for x86 Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2014-07-17 05:05:12 +08:00
# Clocksources require validation of the clocksource against the last
# cycle update - x86/TSC misfeature
config CLOCKSOURCE_VALIDATE_LAST_CYCLE
bool
time: Introduce new GENERIC_TIME_VSYSCALL Now that we moved everyone over to GENERIC_TIME_VSYSCALL_OLD, introduce the new declaration and config option for the new update_vsyscall method. Cc: Tony Luck <tony.luck@intel.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Paul Turner <pjt@google.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
2012-09-12 07:58:13 +08:00
# Timekeeping vsyscall support
config GENERIC_TIME_VSYSCALL
bool
timers: Provide generic Kconfig switches We really don't want all the arch code defining stuff over and over. [ anna-maria: Added missing GENERIC_CMOS_UPDATE switch ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@glx-um.de> Cc: Paul Mundt <lethal@linux-sh.org> Link: http://lkml.kernel.org/r/1337529587.3208.2.camel@dionysos Acked-by: Sam Ravnborg <sam@ravnborg.org>
2012-05-18 15:59:57 +08:00
# Old style timekeeping
config ARCH_USES_GETTIMEOFFSET
bool
# The generic clock events infrastructure
config GENERIC_CLOCKEVENTS
bool
clockevents: Add generic timer broadcast function Currently, the timer broadcast mechanism is defined by a function pointer on struct clock_event_device. As the fundamental mechanism for broadcast is architecture-specific, this means that clock_event_device drivers cannot be shared across multiple architectures. This patch adds an (optional) architecture-specific function for timer tick broadcast, allowing drivers which may require broadcast functionality to be shared across multiple architectures. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Cc: linux-arm-kernel@lists.infradead.org Cc: nico@linaro.org Cc: Will.Deacon@arm.com Cc: Marc.Zyngier@arm.com Cc: john.stultz@linaro.org Link: http://lkml.kernel.org/r/1358183124-28461-3-git-send-email-mark.rutland@arm.com Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-01-15 01:05:22 +08:00
# Architecture can handle broadcast in a driver-agnostic way
config ARCH_HAS_TICK_BROADCAST
bool
timers: Provide generic Kconfig switches We really don't want all the arch code defining stuff over and over. [ anna-maria: Added missing GENERIC_CMOS_UPDATE switch ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@glx-um.de> Cc: Paul Mundt <lethal@linux-sh.org> Link: http://lkml.kernel.org/r/1337529587.3208.2.camel@dionysos Acked-by: Sam Ravnborg <sam@ravnborg.org>
2012-05-18 15:59:57 +08:00
# Clockevents broadcasting infrastructure
config GENERIC_CLOCKEVENTS_BROADCAST
bool
depends on GENERIC_CLOCKEVENTS
timers: Fixup the Kconfig consolidation fallout Sigh, I missed to check which architecture Kconfig files actually include the core Kconfig file. There are a few which did not. So we broke them. Instead of adding the includes to those, we are better off to move the include to init/Kconfig like we did already with irqs and others. This does not change anything for the architectures using the old style periodic timer mode. It just solves the build wreckage there. For those architectures which use the clock events infrastructure it moves the include of the core Kconfig file to "General setup" which is a way more logical place than having it at random locations specified by the architecture specific Kconfigs. Reported-by: Ingo Molnar <mingo@kernel.org> Cc: Anna-Maria Gleixner <anna-maria@glx-um.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-05-22 05:16:18 +08:00
# Automatically adjust the min. reprogramming time for
# clock event device
config GENERIC_CLOCKEVENTS_MIN_ADJUST
bool
timers: Provide generic Kconfig switches We really don't want all the arch code defining stuff over and over. [ anna-maria: Added missing GENERIC_CMOS_UPDATE switch ] Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@glx-um.de> Cc: Paul Mundt <lethal@linux-sh.org> Link: http://lkml.kernel.org/r/1337529587.3208.2.camel@dionysos Acked-by: Sam Ravnborg <sam@ravnborg.org>
2012-05-18 15:59:57 +08:00
# Generic update of CMOS clock
config GENERIC_CMOS_UPDATE
bool
timers: Fixup the Kconfig consolidation fallout Sigh, I missed to check which architecture Kconfig files actually include the core Kconfig file. There are a few which did not. So we broke them. Instead of adding the includes to those, we are better off to move the include to init/Kconfig like we did already with irqs and others. This does not change anything for the architectures using the old style periodic timer mode. It just solves the build wreckage there. For those architectures which use the clock events infrastructure it moves the include of the core Kconfig file to "General setup" which is a way more logical place than having it at random locations specified by the architecture specific Kconfigs. Reported-by: Ingo Molnar <mingo@kernel.org> Cc: Anna-Maria Gleixner <anna-maria@glx-um.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-05-22 05:16:18 +08:00
if GENERIC_CLOCKEVENTS
menu "Timers subsystem"
nohz: Rename CONFIG_NO_HZ to CONFIG_NO_HZ_COMMON We are planning to convert the dynticks Kconfig options layout into a choice menu. The user must be able to easily pick any of the following implementations: constant periodic tick, idle dynticks, full dynticks. As this implies a mutual exclusion, the two dynticks implementions need to converge on the selection of a common Kconfig option in order to ease the sharing of a common infrastructure. It would thus seem pretty natural to reuse CONFIG_NO_HZ to that end. It already implements all the idle dynticks code and the full dynticks depends on all that code for now. So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ. On the other hand we want to stay backward compatible: if CONFIG_NO_HZ is set in an older config file, we want to enable CONFIG_NO_HZ_IDLE by default. But we can't afford both at the same time or we run into a circular dependency: 1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select CONFIG_NO_HZ 2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLE We might be able to support that from Kconfig/Kbuild but it may not be wise to introduce such a confusing behaviour. So to solve this, create a new CONFIG_NO_HZ_COMMON option which gathers the common code between idle and full dynticks (that common code for now is simply the idle dynticks code) and select it from their referring Kconfig. Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ to it for backward compatibility. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
# Core internal switch. Selected by NO_HZ_COMMON / HIGH_RES_TIMERS. This is
timers: Fixup the Kconfig consolidation fallout Sigh, I missed to check which architecture Kconfig files actually include the core Kconfig file. There are a few which did not. So we broke them. Instead of adding the includes to those, we are better off to move the include to init/Kconfig like we did already with irqs and others. This does not change anything for the architectures using the old style periodic timer mode. It just solves the build wreckage there. For those architectures which use the clock events infrastructure it moves the include of the core Kconfig file to "General setup" which is a way more logical place than having it at random locations specified by the architecture specific Kconfigs. Reported-by: Ingo Molnar <mingo@kernel.org> Cc: Anna-Maria Gleixner <anna-maria@glx-um.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-05-22 05:16:18 +08:00
# only related to the tick functionality. Oneshot clockevent devices
kernel/time/Kconfig: Fix typo in comment Fix typo in Kconfig comment text. Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Stephen Boyd <sboyd@codeaurora.org> Cc: Jiri Kosina <trivial@kernel.org> Link: https://lkml.kernel.org/r/0e586dd4-2b27-864e-c252-bc72df52fd01@infradead.org
2017-11-02 02:04:51 +08:00
# are supported independent of this.
timers: Fixup the Kconfig consolidation fallout Sigh, I missed to check which architecture Kconfig files actually include the core Kconfig file. There are a few which did not. So we broke them. Instead of adding the includes to those, we are better off to move the include to init/Kconfig like we did already with irqs and others. This does not change anything for the architectures using the old style periodic timer mode. It just solves the build wreckage there. For those architectures which use the clock events infrastructure it moves the include of the core Kconfig file to "General setup" which is a way more logical place than having it at random locations specified by the architecture specific Kconfigs. Reported-by: Ingo Molnar <mingo@kernel.org> Cc: Anna-Maria Gleixner <anna-maria@glx-um.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-05-22 05:16:18 +08:00
config TICK_ONESHOT
bool
nohz: Rename CONFIG_NO_HZ to CONFIG_NO_HZ_COMMON We are planning to convert the dynticks Kconfig options layout into a choice menu. The user must be able to easily pick any of the following implementations: constant periodic tick, idle dynticks, full dynticks. As this implies a mutual exclusion, the two dynticks implementions need to converge on the selection of a common Kconfig option in order to ease the sharing of a common infrastructure. It would thus seem pretty natural to reuse CONFIG_NO_HZ to that end. It already implements all the idle dynticks code and the full dynticks depends on all that code for now. So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ. On the other hand we want to stay backward compatible: if CONFIG_NO_HZ is set in an older config file, we want to enable CONFIG_NO_HZ_IDLE by default. But we can't afford both at the same time or we run into a circular dependency: 1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select CONFIG_NO_HZ 2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLE We might be able to support that from Kconfig/Kbuild but it may not be wise to introduce such a confusing behaviour. So to solve this, create a new CONFIG_NO_HZ_COMMON option which gathers the common code between idle and full dynticks (that common code for now is simply the idle dynticks code) and select it from their referring Kconfig. Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ to it for backward compatibility. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
config NO_HZ_COMMON
bool
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
select TICK_ONESHOT
nohz: Pack nohz Kconfig option in a menu of choices Now the user has the choice between three implementations of the timer tick: * Static periodic tick * Idle dynticks * Full dynticks At least for now, these are mutually exclusive choices, so let's rely on the proper Kconfig feature to display these to the user. A new entry CONFIG_NO_HZ_IDLE is created and the old CONFIG_NO_HZ maps to it for config file backward compatibility. The old name was too general now that we have more granular dynticks implementations. While at it, add some explanation to help the user on his decision between the 3 entries. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
choice
prompt "Timer tick handling"
default NO_HZ_IDLE if NO_HZ
nohz: Align periodic tick Kconfig with other choices' naming convention Rename CONFIG_PERIODIC_HZ to CONFIG_HZ_PERIODIC in order to stay consistent with other tick implementation entries: CONFIG_HZ_PERIODIC CONFIG_NO_HZ_IDLE CONFIG_NO_HZ_FULL Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-04-13 22:53:35 +08:00
config HZ_PERIODIC
nohz: Pack nohz Kconfig option in a menu of choices Now the user has the choice between three implementations of the timer tick: * Static periodic tick * Idle dynticks * Full dynticks At least for now, these are mutually exclusive choices, so let's rely on the proper Kconfig feature to display these to the user. A new entry CONFIG_NO_HZ_IDLE is created and the old CONFIG_NO_HZ maps to it for config file backward compatibility. The old name was too general now that we have more granular dynticks implementations. While at it, add some explanation to help the user on his decision between the 3 entries. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
bool "Periodic timer ticks (constant rate, no dynticks)"
help
This option keeps the tick running periodically at a constant
rate, even when the CPU doesn't need it.
config NO_HZ_IDLE
bool "Idle dynticks system (tickless idle)"
timers: Fixup the Kconfig consolidation fallout Sigh, I missed to check which architecture Kconfig files actually include the core Kconfig file. There are a few which did not. So we broke them. Instead of adding the includes to those, we are better off to move the include to init/Kconfig like we did already with irqs and others. This does not change anything for the architectures using the old style periodic timer mode. It just solves the build wreckage there. For those architectures which use the clock events infrastructure it moves the include of the core Kconfig file to "General setup" which is a way more logical place than having it at random locations specified by the architecture specific Kconfigs. Reported-by: Ingo Molnar <mingo@kernel.org> Cc: Anna-Maria Gleixner <anna-maria@glx-um.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-05-22 05:16:18 +08:00
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
nohz: Rename CONFIG_NO_HZ to CONFIG_NO_HZ_COMMON We are planning to convert the dynticks Kconfig options layout into a choice menu. The user must be able to easily pick any of the following implementations: constant periodic tick, idle dynticks, full dynticks. As this implies a mutual exclusion, the two dynticks implementions need to converge on the selection of a common Kconfig option in order to ease the sharing of a common infrastructure. It would thus seem pretty natural to reuse CONFIG_NO_HZ to that end. It already implements all the idle dynticks code and the full dynticks depends on all that code for now. So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ. On the other hand we want to stay backward compatible: if CONFIG_NO_HZ is set in an older config file, we want to enable CONFIG_NO_HZ_IDLE by default. But we can't afford both at the same time or we run into a circular dependency: 1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select CONFIG_NO_HZ 2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLE We might be able to support that from Kconfig/Kbuild but it may not be wise to introduce such a confusing behaviour. So to solve this, create a new CONFIG_NO_HZ_COMMON option which gathers the common code between idle and full dynticks (that common code for now is simply the idle dynticks code) and select it from their referring Kconfig. Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ to it for backward compatibility. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
select NO_HZ_COMMON
timers: Fixup the Kconfig consolidation fallout Sigh, I missed to check which architecture Kconfig files actually include the core Kconfig file. There are a few which did not. So we broke them. Instead of adding the includes to those, we are better off to move the include to init/Kconfig like we did already with irqs and others. This does not change anything for the architectures using the old style periodic timer mode. It just solves the build wreckage there. For those architectures which use the clock events infrastructure it moves the include of the core Kconfig file to "General setup" which is a way more logical place than having it at random locations specified by the architecture specific Kconfigs. Reported-by: Ingo Molnar <mingo@kernel.org> Cc: Anna-Maria Gleixner <anna-maria@glx-um.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-05-22 05:16:18 +08:00
help
nohz: Pack nohz Kconfig option in a menu of choices Now the user has the choice between three implementations of the timer tick: * Static periodic tick * Idle dynticks * Full dynticks At least for now, these are mutually exclusive choices, so let's rely on the proper Kconfig feature to display these to the user. A new entry CONFIG_NO_HZ_IDLE is created and the old CONFIG_NO_HZ maps to it for config file backward compatibility. The old name was too general now that we have more granular dynticks implementations. While at it, add some explanation to help the user on his decision between the 3 entries. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
This option enables a tickless idle system: timer interrupts
will only trigger on an as-needed basis when the system is idle.
This is usually interesting for energy saving.
Most of the time you want to say Y here.
timers: Fixup the Kconfig consolidation fallout Sigh, I missed to check which architecture Kconfig files actually include the core Kconfig file. There are a few which did not. So we broke them. Instead of adding the includes to those, we are better off to move the include to init/Kconfig like we did already with irqs and others. This does not change anything for the architectures using the old style periodic timer mode. It just solves the build wreckage there. For those architectures which use the clock events infrastructure it moves the include of the core Kconfig file to "General setup" which is a way more logical place than having it at random locations specified by the architecture specific Kconfigs. Reported-by: Ingo Molnar <mingo@kernel.org> Cc: Anna-Maria Gleixner <anna-maria@glx-um.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-05-22 05:16:18 +08:00
nohz: Switch from "extended nohz" to "full nohz" based naming "Extended nohz" was used as a naming base for the full dynticks API and Kconfig symbols. It reflects the fact the system tries to stop the tick in more places than just idle. But that "extended" name is a bit opaque and vague. Rename it to "full" makes it clearer what the system tries to do under this config: try to shutdown the tick anytime it can. The various constraints that prevent that to happen shouldn't be considered as fundamental properties of this feature but rather technical issues that may be solved in the future. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-04-12 22:45:34 +08:00
config NO_HZ_FULL
nohz: Improve a bit the full dynticks Kconfig documentation Remove the "single task" statement from CONFIG_NO_HZ_FULL title. The constraint can be invalidated when tasks from other sched classes than SCHED_FAIR are running. Moreover it's possible that hrtick join the party in the future. Also add a line about the dependency on SMP. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-04-13 23:04:04 +08:00
bool "Full dynticks system (tickless)"
nohz: Rename CONFIG_NO_HZ to CONFIG_NO_HZ_COMMON We are planning to convert the dynticks Kconfig options layout into a choice menu. The user must be able to easily pick any of the following implementations: constant periodic tick, idle dynticks, full dynticks. As this implies a mutual exclusion, the two dynticks implementions need to converge on the selection of a common Kconfig option in order to ease the sharing of a common infrastructure. It would thus seem pretty natural to reuse CONFIG_NO_HZ to that end. It already implements all the idle dynticks code and the full dynticks depends on all that code for now. So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ. On the other hand we want to stay backward compatible: if CONFIG_NO_HZ is set in an older config file, we want to enable CONFIG_NO_HZ_IDLE by default. But we can't afford both at the same time or we run into a circular dependency: 1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select CONFIG_NO_HZ 2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLE We might be able to support that from Kconfig/Kbuild but it may not be wise to introduce such a confusing behaviour. So to solve this, create a new CONFIG_NO_HZ_COMMON option which gathers the common code between idle and full dynticks (that common code for now is simply the idle dynticks code) and select it from their referring Kconfig. Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ to it for backward compatibility. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
# NO_HZ_COMMON dependency
nohz: Unhide full dynticks feature from its dependencies The full dynticks feature only shows up when all its Kconfig dependencies are met (RCU nocbs, RCU user mode, ...) This is far from being user friendly as those who want to activate this feature need to look into the Kconfig files and iterate through each dependency then activate these by hand in order to show and select the full dynticks Kconfig option. So process the other way around: show up the Kconfig option if the minimal low level dependencies are met and activate the high level ones when we enable the feature. Note there is one exception in the picture: CONFIG_VIRT_CPU_ACCOUNTING_GEN is part of a Kconfig choice menu and it appears we can't select it from another Kconfig selection when it's under such layout. So for now this particular item stays as a passive dependency. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
nohz: Improve a bit the full dynticks Kconfig documentation Remove the "single task" statement from CONFIG_NO_HZ_FULL title. The constraint can be invalidated when tasks from other sched classes than SCHED_FAIR are running. Moreover it's possible that hrtick join the party in the future. Also add a line about the dependency on SMP. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-04-13 23:04:04 +08:00
# We need at least one periodic CPU for timekeeping
depends on SMP
depends on HAVE_CONTEXT_TRACKING
nohz: Select VIRT_CPU_ACCOUNTING_GEN from full dynticks config Turn the full dynticks passive dependency on VIRT_CPU_ACCOUNTING_GEN to an active one. The full dynticks Kconfig is currently hidden behind the full dynticks cputime accounting, which is an awkward and counter-intuitive layout: the user first has to select the dynticks cputime accounting in order to make the full dynticks feature to be visible. We definetly want it the other way around. The usual way to perform this kind of active dependency is use "select" on the depended target. Now we can't use the Kconfig "select" instruction when the target is a "choice". So this patch inspires on how the RCU subsystem Kconfig interact with its dependencies on SMP and PREEMPT: we make sure that cputime accounting can't propose another option than VIRT_CPU_ACCOUNTING_GEN when NO_HZ_FULL is selected by using the right "depends on" instruction for each cputime accounting choices. v2: Keep full dynticks cputime accounting available even without full dynticks, as per Paul McKenney's suggestion. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-04-26 21:16:31 +08:00
# VIRT_CPU_ACCOUNTING_GEN dependency
vtime: Add HAVE_VIRT_CPU_ACCOUNTING_GEN Kconfig With VIRT_CPU_ACCOUNTING_GEN, cputime_t becomes 64-bit. In order to use that feature, arch code should be audited to ensure there are no races in concurrent read/write of cputime_t. For example, reading/writing 64-bit cputime_t on some 32-bit arches may require multiple accesses for low and high value parts, so proper locking is needed to protect against concurrent accesses. Therefore, add CONFIG_HAVE_VIRT_CPU_ACCOUNTING_GEN which arches can enable after they've been audited for potential races. This option is automatically enabled on 64-bit platforms. Feature requested by Frederic Weisbecker. Signed-off-by: Kevin Hilman <khilman@linaro.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Arm Linux <linux-arm-kernel@lists.infradead.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2013-09-17 06:28:21 +08:00
depends on HAVE_VIRT_CPU_ACCOUNTING_GEN
nohz: Rename CONFIG_NO_HZ to CONFIG_NO_HZ_COMMON We are planning to convert the dynticks Kconfig options layout into a choice menu. The user must be able to easily pick any of the following implementations: constant periodic tick, idle dynticks, full dynticks. As this implies a mutual exclusion, the two dynticks implementions need to converge on the selection of a common Kconfig option in order to ease the sharing of a common infrastructure. It would thus seem pretty natural to reuse CONFIG_NO_HZ to that end. It already implements all the idle dynticks code and the full dynticks depends on all that code for now. So ideally the choice menu would propose CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED then both would select CONFIG_NO_HZ. On the other hand we want to stay backward compatible: if CONFIG_NO_HZ is set in an older config file, we want to enable CONFIG_NO_HZ_IDLE by default. But we can't afford both at the same time or we run into a circular dependency: 1) CONFIG_NO_HZ_IDLE and CONFIG_NO_HZ_EXTENDED both select CONFIG_NO_HZ 2) If CONFIG_NO_HZ is set, we default to CONFIG_NO_HZ_IDLE We might be able to support that from Kconfig/Kbuild but it may not be wise to introduce such a confusing behaviour. So to solve this, create a new CONFIG_NO_HZ_COMMON option which gathers the common code between idle and full dynticks (that common code for now is simply the idle dynticks code) and select it from their referring Kconfig. Then we'll later create CONFIG_NO_HZ_IDLE and map CONFIG_NO_HZ to it for backward compatibility. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
select NO_HZ_COMMON
nohz: Unhide full dynticks feature from its dependencies The full dynticks feature only shows up when all its Kconfig dependencies are met (RCU nocbs, RCU user mode, ...) This is far from being user friendly as those who want to activate this feature need to look into the Kconfig files and iterate through each dependency then activate these by hand in order to show and select the full dynticks Kconfig option. So process the other way around: show up the Kconfig option if the minimal low level dependencies are met and activate the high level ones when we enable the feature. Note there is one exception in the picture: CONFIG_VIRT_CPU_ACCOUNTING_GEN is part of a Kconfig choice menu and it appears we can't select it from another Kconfig selection when it's under such layout. So for now this particular item stays as a passive dependency. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
select RCU_NOCB_CPU
nohz: Select VIRT_CPU_ACCOUNTING_GEN from full dynticks config Turn the full dynticks passive dependency on VIRT_CPU_ACCOUNTING_GEN to an active one. The full dynticks Kconfig is currently hidden behind the full dynticks cputime accounting, which is an awkward and counter-intuitive layout: the user first has to select the dynticks cputime accounting in order to make the full dynticks feature to be visible. We definetly want it the other way around. The usual way to perform this kind of active dependency is use "select" on the depended target. Now we can't use the Kconfig "select" instruction when the target is a "choice". So this patch inspires on how the RCU subsystem Kconfig interact with its dependencies on SMP and PREEMPT: we make sure that cputime accounting can't propose another option than VIRT_CPU_ACCOUNTING_GEN when NO_HZ_FULL is selected by using the right "depends on" instruction for each cputime accounting choices. v2: Keep full dynticks cputime accounting available even without full dynticks, as per Paul McKenney's suggestion. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-04-26 21:16:31 +08:00
select VIRT_CPU_ACCOUNTING_GEN
nohz: New APIs to re-evaluate the tick on full dynticks CPUs Provide two new helpers in order to notify the full dynticks CPUs about some internal system changes against which they may reconsider the state of their tick. Some practical examples include: posix cpu timers, perf tick and sched clock tick. For now the notifying handler, implemented through IPIs, is a stub that will be implemented when we get the tick stop/restart infrastructure in. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-04-18 06:15:40 +08:00
select IRQ_WORK
nohz: Unhide full dynticks feature from its dependencies The full dynticks feature only shows up when all its Kconfig dependencies are met (RCU nocbs, RCU user mode, ...) This is far from being user friendly as those who want to activate this feature need to look into the Kconfig files and iterate through each dependency then activate these by hand in order to show and select the full dynticks Kconfig option. So process the other way around: show up the Kconfig option if the minimal low level dependencies are met and activate the high level ones when we enable the feature. Note there is one exception in the picture: CONFIG_VIRT_CPU_ACCOUNTING_GEN is part of a Kconfig choice menu and it appears we can't select it from another Kconfig selection when it's under such layout. So for now this particular item stays as a passive dependency. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
help
Adaptively try to shutdown the tick whenever possible, even when
nohz: Basic full dynticks interface For extreme usecases such as Real Time or HPC, having the ability to shutdown the tick when a single task runs on a CPU is a desired feature: * Reducing the amount of interrupts improves throughput for CPU-bound tasks. The CPU is less distracted from its real job, from an execution time and from the cache point of views. * This also improve latency response as we have less critical sections. Start with introducing a very simple interface to define full dynticks CPU: use a boot time option defined cpumask through the "nohz_extended=" kernel parameter. CPUs that are part of this range will have their tick shutdown whenever possible: provided they run a single task and they don't do kernel activity that require the periodic tick. These details will be later documented in Documentation/* An online CPU must be kept outside this range to handle the timekeeping. Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2012-12-19 00:32:19 +08:00
the CPU is running tasks. Typically this requires running a single
task on the CPU. Chances for running tickless are maximized when
the task mostly runs in userspace and has few kernel activity.
nohz: Switch from "extended nohz" to "full nohz" based naming "Extended nohz" was used as a naming base for the full dynticks API and Kconfig symbols. It reflects the fact the system tries to stop the tick in more places than just idle. But that "extended" name is a bit opaque and vague. Rename it to "full" makes it clearer what the system tries to do under this config: try to shutdown the tick anytime it can. The various constraints that prevent that to happen shouldn't be considered as fundamental properties of this feature but rather technical issues that may be solved in the future. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-04-12 22:45:34 +08:00
You need to fill up the nohz_full boot parameter with the
nohz: Basic full dynticks interface For extreme usecases such as Real Time or HPC, having the ability to shutdown the tick when a single task runs on a CPU is a desired feature: * Reducing the amount of interrupts improves throughput for CPU-bound tasks. The CPU is less distracted from its real job, from an execution time and from the cache point of views. * This also improve latency response as we have less critical sections. Start with introducing a very simple interface to define full dynticks CPU: use a boot time option defined cpumask through the "nohz_extended=" kernel parameter. CPUs that are part of this range will have their tick shutdown whenever possible: provided they run a single task and they don't do kernel activity that require the periodic tick. These details will be later documented in Documentation/* An online CPU must be kept outside this range to handle the timekeeping. Suggested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2012-12-19 00:32:19 +08:00
desired range of dynticks CPUs.
This is implemented at the expense of some overhead in user <-> kernel
transitions: syscalls, exceptions and interrupts. Even when it's
dynamically off.
Say N.
nohz: Pack nohz Kconfig option in a menu of choices Now the user has the choice between three implementations of the timer tick: * Static periodic tick * Idle dynticks * Full dynticks At least for now, these are mutually exclusive choices, so let's rely on the proper Kconfig feature to display these to the user. A new entry CONFIG_NO_HZ_IDLE is created and the old CONFIG_NO_HZ maps to it for config file backward compatibility. The old name was too general now that we have more granular dynticks implementations. While at it, add some explanation to help the user on his decision between the 3 entries. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2011-08-11 05:21:01 +08:00
endchoice
nohz: New option to default all CPUs in full dynticks range Provide a new kernel config that defaults all CPUs to be part of the full dynticks range, except the boot one for timekeeping. This default setting is overriden by the nohz_full= boot option if passed by the user. This is helpful for those who don't need a finegrained range of full dynticks CPU and also for automated testing. Suggested-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-03-27 08:17:22 +08:00
config NO_HZ_FULL_ALL
nohz: ensure users are aware boot CPU is not NO_HZ_FULL This bit of information is in the Kconfig help text: "Note the boot CPU will still be kept outside the range to handle the timekeeping duty." However neither the variable NO_HZ_FULL_ALL, or the prompt convey this important detail, so lets add it to the prompt to make it more explicitly obvious to the average user. Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1391711781-7466-1-git-send-email-paul.gortmaker@windriver.com Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
2014-02-07 02:36:21 +08:00
bool "Full dynticks system on all CPUs by default (except CPU 0)"
nohz: New option to default all CPUs in full dynticks range Provide a new kernel config that defaults all CPUs to be part of the full dynticks range, except the boot one for timekeeping. This default setting is overriden by the nohz_full= boot option if passed by the user. This is helpful for those who don't need a finegrained range of full dynticks CPU and also for automated testing. Suggested-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-03-27 08:17:22 +08:00
depends on NO_HZ_FULL
help
If the user doesn't pass the nohz_full boot option to
define the range of full dynticks CPUs, consider that all
CPUs in the system are full dynticks by default.
Note the boot CPU will still be kept outside the range to
handle the timekeeping duty.
nohz: Fix old dynticks idle Kconfig backward compatibility In order to enforce backward compatibility with older config files, we want the new dynticks-idle Kconfig entry to default its value to the one of the old CONFIG_NO_HZ symbol if present. Namely we want: config NO_HZ # old obsolete dynticks idle symbol bool config NO_HZ_IDLE # new dynticks idle symbol default NO_HZ However Kconfig prevents this to work if the old symbol is not visible. And this is currently the case because NO_HZ lacks a title in order to show it in make oldconfig and alike. To fix this, bring a minimal title and help text to the obsolete Kconfig entry that explains its purpose. This makes the "defaulting" to work. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Christoph Lameter <cl@linux.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Gilad Ben Yossef <gilad@benyossef.com> Cc: Hakan Akkan <hakanakkan@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Kevin Hilman <khilman@linaro.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2013-04-12 22:40:12 +08:00
config NO_HZ
bool "Old Idle dynticks config"
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
help
This is the old config entry that enables dynticks idle.
We keep it around for a little while to enforce backward
compatibility with older config files.
timers: Fixup the Kconfig consolidation fallout Sigh, I missed to check which architecture Kconfig files actually include the core Kconfig file. There are a few which did not. So we broke them. Instead of adding the includes to those, we are better off to move the include to init/Kconfig like we did already with irqs and others. This does not change anything for the architectures using the old style periodic timer mode. It just solves the build wreckage there. For those architectures which use the clock events infrastructure it moves the include of the core Kconfig file to "General setup" which is a way more logical place than having it at random locations specified by the architecture specific Kconfigs. Reported-by: Ingo Molnar <mingo@kernel.org> Cc: Anna-Maria Gleixner <anna-maria@glx-um.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2012-05-22 05:16:18 +08:00
config HIGH_RES_TIMERS
bool "High Resolution Timer Support"
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
select TICK_ONESHOT
help
This option enables high resolution timer support. If your
hardware is not capable then this option only increases
the size of the kernel image.
endmenu
endif