lkml.org 
[lkml]   [2021]   [Jun]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH 1/2] sched: Add default dynamic preempt mode Kconfig
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

\
 
 \ /
  Last update: 2021-06-08 16:05    [W:0.075 / U:0.372 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site