Messages in this thread Patch in this message | | | Date | Tue, 8 Jun 2021 16:04:47 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] sched: Add default dynamic preempt mode Kconfig |
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On Tue, Jun 08, 2021 at 03:55:09PM +0200, Peter Zijlstra wrote: > Urgh, would something like this work? > > --- > kernel/Kconfig.preempt | 64 ++++++++++++++++++++++++++++++++++++++++---------- > 1 file changed, 51 insertions(+), 13 deletions(-) > > diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt > index bd7c4147b9a8..43c68a806e4e 100644 > --- a/kernel/Kconfig.preempt > +++ b/kernel/Kconfig.preempt > @@ -1,11 +1,25 @@ > # SPDX-License-Identifier: GPL-2.0-only > > +config PREEMPT_COUNT > + bool > + > +config PREEMPTION > + bool > + select PREEMPT_COUNT > + > +config PREEMPT_DYNAMIC_OPTION > + bool > + help > + Symbol that gates availablility of PREEMPT_DYNAMIC, selected > + by preemption models that can be dynamically selected. > + > choice > prompt "Preemption Model" > + default PREEMPT_TYPE_NONE > > +config PREEMPT_TYPE_NONE > bool "No Forced Preemption (Server)" > + select PREEMPT_DYNAMIC_OPTION if HAVE_PREEMPT_DYNAMIC > help > This is the traditional Linux preemption model, geared towards > throughput. It will still provide good latencies most of the > @@ -17,9 +31,10 @@ config PREEMPT_NONE > raw processing power of the kernel, irrespective of scheduling > latencies. > > +config PREEMPT_TYPE_VOLUNTARY > bool "Voluntary Kernel Preemption (Desktop)" > depends on !ARCH_NO_PREEMPT > + select PREEMPT_DYNAMIC_OPTION if HAVE_PREEMPT_DYNAMIC > help > This option reduces the latency of the kernel by adding more > "explicit preemption points" to the kernel code. These new > @@ -35,12 +50,10 @@ config PREEMPT_VOLUNTARY > > Select this if you are building a kernel for a desktop system. > > -config PREEMPT > +config PREEMPT_TYPE_FULL > bool "Preemptible Kernel (Low-Latency Desktop)" > depends on !ARCH_NO_PREEMPT > + select PREEMPT_DYNAMIC_OPTION if HAVE_PREEMPT_DYNAMIC > help > This option reduces the latency of the kernel by making > all kernel code (that is not executing in a critical section) > @@ -75,15 +88,24 @@ config PREEMPT_RT > > endchoice > > +# default model for PREEMPT_DYNAMIC > > +config PREEMPT_DYNAMIC_NONE > + bool > > +config PREEMPT_DYNAMIC_VOLUNTARY > + bool > + > +config PREEMPT_DYNAMIC_FULL > bool > + > +config PREEMPT_DYNAMIC > + bool "Dynamic Preemption Mode" > + depends on PREEMPT_DYNAMIC_OPTION > + select PREEMPT > + select PREEMPT_DYNAMIC_NONE if PREEMPT_TYPE_NONE > + select PREEMPT_DYNAMIC_VOLUNTARY if PREEMPT_TYPE_VOLUNTARY > + select PREEMPT_DYNAMIC_FULL if PREEMPT_TYPE_FULL
Arguably PREEMPT_DYNAMIC_{NONE,VOLUNTARY,FULL} are superfluous and the default selection can use PREEMPT_TYPE_*.
> help > This option allows to define the preemption model on the kernel > command line parameter and thus override the default preemption > @@ -100,6 +122,22 @@ config PREEMPT_DYNAMIC > Interesting if you want the same pre-built kernel should be used for > both Server and Desktop workloads. > > +# actual preemption model > + > +config PREEMPT_NONE > + bool > + default y if !PREEMPT_DYNAMIC && PREEMPT_TYPE_NONE > + > +config PREEMPT_VOLUNTARY > + bool > + default y if !PREEMPT_DYNAMIC && PREEMPT_TYPE_VOLUNTARY > + > +config PREEMPT > + bool > + default y if !PREEMPT_DYNAMIC && PREEMPT_TYPE_FULL > + select PREEMPTION > + select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK > + > config SCHED_CORE > bool "Core Scheduling for SMT" > default y
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