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From: Frederic Weisbecker <frederic@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] sched: Add default dynamic preempt mode Kconfig
Date: Wed, 9 Jun 2021 13:27:50 +0200	[thread overview]
Message-ID: <20210609112750.GC104634@lothringen> (raw)
In-Reply-To: <YL94/8cSr2R2wiTa@hirez.programming.kicks-ass.net>

On Tue, Jun 08, 2021 at 04:04:47PM +0200, Peter Zijlstra wrote:
> 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_*.

Right, I'll try that.

Thanks.

  reply	other threads:[~2021-06-09 11:27 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-08 12:04 [PATCH 0/2] sched: Define default preempt dynamic boot mode on Kconfig Frederic Weisbecker
2021-06-08 12:04 ` [PATCH 1/2] sched: Add default dynamic preempt mode Kconfig Frederic Weisbecker
2021-06-08 13:55   ` Peter Zijlstra
2021-06-08 14:04     ` Peter Zijlstra
2021-06-09 11:27       ` Frederic Weisbecker [this message]
2021-06-09 11:13     ` Frederic Weisbecker
2021-06-08 13:55   ` Peter Zijlstra
2021-06-09 11:25     ` Frederic Weisbecker
2021-06-08 12:04 ` [PATCH 2/2] sched: Always print out preempt dynamic state Frederic Weisbecker
2021-06-08 13:56   ` Peter Zijlstra

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