2015-04-21 21:29:57

by Pranith Kumar

Subject: [RFC PATCH] rcu: config: Remove prompt for RCU implementation

The RCU implementation which is chosen is dependent on PREEMPT and SMP config
options and is not really a user-selectable choice. The following change will
remove the menu entry and will be derived from the above two options.

Signed-off-by: Pranith Kumar <[email protected]>
---
init/Kconfig | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 0b37750..7707e4a 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -463,13 +463,9 @@ endmenu # "CPU/Task time and stats accounting"

menu "RCU Subsystem"

-choice
- prompt "RCU Implementation"
- default TREE_RCU
-
config TREE_RCU
- bool "Tree-based hierarchical RCU"
- depends on !PREEMPT && SMP
+ bool
+ default y if !PREEMPT && SMP
help
This option selects the RCU implementation that is
designed for very large SMP system with hundreds or
@@ -477,8 +473,8 @@ config TREE_RCU
smaller systems.

config PREEMPT_RCU
- bool "Preemptible tree-based hierarchical RCU"
- depends on PREEMPT
+ bool
+ default y if PREEMPT
help
This option selects the RCU implementation that is
designed for very large SMP systems with hundreds or
@@ -489,16 +485,14 @@ config PREEMPT_RCU
Select this option if you are unsure.

config TINY_RCU
- bool "UP-only small-memory-footprint RCU"
- depends on !PREEMPT && !SMP
+ bool
+ default y if !PREEMPT && !SMP
help
This option selects the RCU implementation that is
designed for UP systems from which real-time response
is not required. This option greatly reduces the
memory footprint of RCU.

-endchoice
-
config RCU_EXPERT
bool "Make expert-level adjustments to RCU configuration"
default n
--
1.9.1

2015-04-22 01:18:28

by Paul E. McKenney

Subject: Re: [RFC PATCH] rcu: config: Remove prompt for RCU implementation

On Tue, Apr 21, 2015 at 05:29:42PM -0400, Pranith Kumar wrote:
> The RCU implementation which is chosen is dependent on PREEMPT and SMP config
> options and is not really a user-selectable choice. The following change will
> remove the menu entry and will be derived from the above two options.
>
> Signed-off-by: Pranith Kumar <[email protected]>

Hmmm... I guess that there isn't much point in calling something a
"choice" when it hasn't really been a choice for quite a few years
now. I queued this, and have started testing it.

Thanx, Paul

> ---
> init/Kconfig | 18 ++++++------------
> 1 file changed, 6 insertions(+), 12 deletions(-)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 0b37750..7707e4a 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -463,13 +463,9 @@ endmenu # "CPU/Task time and stats accounting"
>
> menu "RCU Subsystem"
>
> -choice
> - prompt "RCU Implementation"
> - default TREE_RCU
> -
> config TREE_RCU
> - bool "Tree-based hierarchical RCU"
> - depends on !PREEMPT && SMP
> + bool
> + default y if !PREEMPT && SMP
> help
> This option selects the RCU implementation that is
> designed for very large SMP system with hundreds or
> @@ -477,8 +473,8 @@ config TREE_RCU
> smaller systems.
>
> config PREEMPT_RCU
> - bool "Preemptible tree-based hierarchical RCU"
> - depends on PREEMPT
> + bool
> + default y if PREEMPT
> help
> This option selects the RCU implementation that is
> designed for very large SMP systems with hundreds or
> @@ -489,16 +485,14 @@ config PREEMPT_RCU
> Select this option if you are unsure.
>
> config TINY_RCU
> - bool "UP-only small-memory-footprint RCU"
> - depends on !PREEMPT && !SMP
> + bool
> + default y if !PREEMPT && !SMP
> help
> This option selects the RCU implementation that is
> designed for UP systems from which real-time response
> is not required. This option greatly reduces the
> memory footprint of RCU.
>
> -endchoice
> -
> config RCU_EXPERT
> bool "Make expert-level adjustments to RCU configuration"
> default n
> --
> 1.9.1
>