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Message-Id: <20231107215742.363031-17-ankur.a.arora@oracle.com>
Date: Tue, 7 Nov 2023 13:57:02 -0800
From: Ankur Arora <ankur.a.arora@...cle.com>
To: linux-kernel@...r.kernel.org
Cc: tglx@...utronix.de, peterz@...radead.org,
torvalds@...ux-foundation.org, paulmck@...nel.org,
linux-mm@...ck.org, x86@...nel.org, akpm@...ux-foundation.org,
luto@...nel.org, bp@...en8.de, dave.hansen@...ux.intel.com,
hpa@...or.com, mingo@...hat.com, juri.lelli@...hat.com,
vincent.guittot@...aro.org, willy@...radead.org, mgorman@...e.de,
jon.grimm@....com, bharata@....com, raghavendra.kt@....com,
boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
jgross@...e.com, andrew.cooper3@...rix.com, mingo@...nel.org,
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anton.ivanov@...bridgegreys.com, mattst88@...il.com,
krypton@...ich-teichert.org, rostedt@...dmis.org,
David.Laight@...LAB.COM, richard@....at, mjguzik@...il.com,
Ankur Arora <ankur.a.arora@...cle.com>
Subject: [RFC PATCH 16/86] Revert "sched: Provide Kconfig support for default dynamic preempt mode"
This reverts commit c597bfddc9e9e8a63817252b67c3ca0e544ace26.
Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
kernel/Kconfig.preempt | 32 +++++++++-----------------------
kernel/sched/core.c | 29 +++--------------------------
2 files changed, 12 insertions(+), 49 deletions(-)
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 60f1bfc3c7b2..5876e30c5740 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -2,11 +2,10 @@
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
help
This is the traditional Linux preemption model, geared towards
throughput. It will still provide good latencies most of the
@@ -18,10 +17,9 @@ 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
help
This option reduces the latency of the kernel by adding more
"explicit preemption points" to the kernel code. These new
@@ -37,10 +35,12 @@ 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 PREEMPTION
+ select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK
+ select PREEMPT_DYNAMIC 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)
@@ -58,7 +58,7 @@ config PREEMPT_BEHAVIOUR
config PREEMPT_RT
bool "Fully Preemptible Kernel (Real-Time)"
- depends on EXPERT && ARCH_SUPPORTS_RT && !PREEMPT_DYNAMIC
+ depends on EXPERT && ARCH_SUPPORTS_RT
select PREEMPTION
help
This option turns the kernel into a real-time kernel by replacing
@@ -75,17 +75,6 @@ config PREEMPT_RT
endchoice
-config PREEMPT_NONE
- bool
-
-config PREEMPT_VOLUNTARY
- bool
-
-config PREEMPT
- bool
- select PREEMPTION
- select UNINLINE_SPIN_UNLOCK if !ARCH_INLINE_SPIN_UNLOCK
-
config PREEMPT_COUNT
bool
@@ -94,10 +83,7 @@ config PREEMPTION
select PREEMPT_COUNT
config PREEMPT_DYNAMIC
- bool "Preemption behaviour defined on boot"
- depends on HAVE_PREEMPT_DYNAMIC
- select PREEMPT
- default y
+ bool
help
This option allows to define the preemption model on the kernel
command line parameter and thus override the default preemption
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index d3828d90bf84..12f255e038ed 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6991,13 +6991,12 @@ EXPORT_STATIC_CALL_TRAMP(preempt_schedule_notrace);
*/
enum {
- preempt_dynamic_undefined = -1,
- preempt_dynamic_none,
+ preempt_dynamic_none = 0,
preempt_dynamic_voluntary,
preempt_dynamic_full,
};
-int preempt_dynamic_mode = preempt_dynamic_undefined;
+int preempt_dynamic_mode = preempt_dynamic_full;
int sched_dynamic_mode(const char *str)
{
@@ -7070,27 +7069,7 @@ static int __init setup_preempt_mode(char *str)
}
__setup("preempt=", setup_preempt_mode);
-static void __init preempt_dynamic_init(void)
-{
- if (preempt_dynamic_mode == preempt_dynamic_undefined) {
- if (IS_ENABLED(CONFIG_PREEMPT_NONE_BEHAVIOUR)) {
- sched_dynamic_update(preempt_dynamic_none);
- } else if (IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY_BEHAVIOUR)) {
- sched_dynamic_update(preempt_dynamic_voluntary);
- } else {
- /* Default static call setting, nothing to do */
- WARN_ON_ONCE(!IS_ENABLED(CONFIG_PREEMPT_BEHAVIOUR));
- preempt_dynamic_mode = preempt_dynamic_full;
- pr_info("Dynamic Preempt: full\n");
- }
- }
-}
-
-#else /* !CONFIG_PREEMPT_DYNAMIC */
-
-static inline void preempt_dynamic_init(void) { }
-
-#endif /* #ifdef CONFIG_PREEMPT_DYNAMIC */
+#endif /* CONFIG_PREEMPT_DYNAMIC */
/*
* This is the entry point to schedule() from kernel preemption
@@ -9966,8 +9945,6 @@ void __init sched_init(void)
init_uclamp();
- preempt_dynamic_init();
-
scheduler_running = 1;
}
--
2.31.1
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