Messages in this thread Patch in this message | | | Date | Wed, 10 Nov 2021 17:49:42 +0100 | From | Frederic Weisbecker <> | Subject | Re: [PATCH] sched: Split preemption model selection between DYNAMIC & !DYNAMIC |
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On Wed, Nov 10, 2021 at 02:45:45PM +0000, Valentin Schneider wrote: > On 10/11/21 11:24, Valentin Schneider wrote: > > Following Frederic's _STATIC suggestion, I got to the below. The nice thing > > is if a defconfig picks say PREEMPT_VOLUNTARY and the arch supports > > PREEMPT_DYNAMIC, then it'll pick PREEMPT_VOLUNTARY_BEHAVIOUR. The less nice > > thing is that we end up selecting PREEMPT_STATIC for PREEMPT_DYNAMIC > > kernels, naming's hard... Maybe _BUILD rather than _STATIC? > > > > And now without a legacy compatibility layer crud... > > --- > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index 2776423a587e..9c7d774ef809 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -88,7 +88,7 @@ > struct completion; > struct user; > > -#ifdef CONFIG_PREEMPT_VOLUNTARY > +#ifdef CONFIG_PREEMPT_VOLUNTARY_BUILD > > extern int __cond_resched(void); > # define might_resched() __cond_resched() > diff --git a/include/linux/vermagic.h b/include/linux/vermagic.h > index 1eaaa93c37bf..f2b71920024c 100644 > --- a/include/linux/vermagic.h > +++ b/include/linux/vermagic.h > @@ -15,7 +15,7 @@ > #else > #define MODULE_VERMAGIC_SMP "" > #endif > -#ifdef CONFIG_PREEMPT > +#ifdef CONFIG_PREEMPT_BUILD > #define MODULE_VERMAGIC_PREEMPT "preempt " > #elif defined(CONFIG_PREEMPT_RT) > #define MODULE_VERMAGIC_PREEMPT "preempt_rt " > @@ -39,9 +39,9 @@ > #define MODULE_RANDSTRUCT_PLUGIN > #endif > > -#define VERMAGIC_STRING \ > +#define VERMAGIC_STRING \ > UTS_RELEASE " " \ > - MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT \ > + MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT \ > MODULE_VERMAGIC_MODULE_UNLOAD MODULE_VERMAGIC_MODVERSIONS \ > MODULE_ARCH_VERMAGIC \ > MODULE_RANDSTRUCT_PLUGIN > diff --git a/init/Makefile b/init/Makefile > index 2846113677ee..04eeee12c076 100644 > --- a/init/Makefile > +++ b/init/Makefile > @@ -30,7 +30,7 @@ $(obj)/version.o: include/generated/compile.h > quiet_cmd_compile.h = CHK $@ > cmd_compile.h = \ > $(CONFIG_SHELL) $(srctree)/scripts/mkcompile_h $@ \ > - "$(UTS_MACHINE)" "$(CONFIG_SMP)" "$(CONFIG_PREEMPT)" \ > + "$(UTS_MACHINE)" "$(CONFIG_SMP)" "$(CONFIG_PREEMPT_BUILD)" \ > "$(CONFIG_PREEMPT_RT)" $(CONFIG_CC_VERSION_TEXT) "$(LD)" > > include/generated/compile.h: FORCE > diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt > index 60f1bfc3c7b2..ce77f0265660 100644 > --- a/kernel/Kconfig.preempt > +++ b/kernel/Kconfig.preempt > @@ -1,12 +1,23 @@ > # SPDX-License-Identifier: GPL-2.0-only > > +config PREEMPT_NONE_BUILD > + bool > + > +config PREEMPT_VOLUNTARY_BUILD > + bool > + > +config PREEMPT_BUILD > + bool > + select PREEMPTION > + select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK > + > choice > prompt "Preemption Model" > - default PREEMPT_NONE_BEHAVIOUR > + default PREEMPT_NONE > > -config PREEMPT_NONE_BEHAVIOUR > +config PREEMPT_NONE > bool "No Forced Preemption (Server)" > - select PREEMPT_NONE if !PREEMPT_DYNAMIC > + select PREEMPT_NONE_BUILD if !PREEMPT_DYNAMIC > help > This is the traditional Linux preemption model, geared towards > throughput. It will still provide good latencies most of the > @@ -18,10 +29,10 @@ config PREEMPT_NONE_BEHAVIOUR > raw processing power of the kernel, irrespective of scheduling > latencies. > > -config PREEMPT_VOLUNTARY_BEHAVIOUR > +config PREEMPT_VOLUNTARY > bool "Voluntary Kernel Preemption (Desktop)" > depends on !ARCH_NO_PREEMPT > - select PREEMPT_VOLUNTARY if !PREEMPT_DYNAMIC > + select PREEMPT_VOLUNTARY_BUILD if !PREEMPT_DYNAMIC > help > This option reduces the latency of the kernel by adding more > "explicit preemption points" to the kernel code. These new > @@ -37,10 +48,10 @@ config PREEMPT_VOLUNTARY_BEHAVIOUR > > Select this if you are building a kernel for a desktop system. > > -config PREEMPT_BEHAVIOUR > +config PREEMPT > bool "Preemptible Kernel (Low-Latency Desktop)" > depends on !ARCH_NO_PREEMPT > - select PREEMPT > + select PREEMPT_BUILD > help > This option reduces the latency of the kernel by making > all kernel code (that is not executing in a critical section)
Looks nicer that way!
But don't forget to also update preempt_dynamic_init().
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