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From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Kirill Tkhai <tkhai@yandex.ru>,
	Kirill Tkhai <ktkhai@virtuozzo.com>,
	Peter Zijlstra <peterz@infradead.org>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"juri.lelli@redhat.com" <juri.lelli@redhat.com>,
	"vincent.guittot@linaro.org" <vincent.guittot@linaro.org>,
	"dietmar.eggemann@arm.com" <dietmar.eggemann@arm.com>,
	"bsegall@google.com" <bsegall@google.com>,
	"mgorman@suse.de" <mgorman@suse.de>,
	Ingo Molnar <mingo@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: [RFC][PATCH 2/4] sched: Have sched_class_highest define by vmlinux.lds.h
Date: Thu, 19 Dec 2019 16:44:53 -0500
Message-ID: <20191219214558.682913590@goodmis.org> (raw)
In-Reply-To: <20191219214451.340746474@goodmis.org>

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

Now that the sched_class descriptors are defined by the linker script, and
this needs to be aware of the existance of stop_sched_class when SMP is
enabled or not, as it is used as the "highest" priority when defined. Move
the declaration of sched_class_highest to the same location in the linker
script that inserts stop_sched_class, and this will also make it easier to
see what should be defined as the highest class, as this linker script
location defines the priorities as well.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 include/asm-generic/vmlinux.lds.h | 11 ++++++++++-
 kernel/sched/sched.h              |  9 +++------
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 772d961c69a5..1c14c4ddf785 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -109,9 +109,16 @@
 #endif
 
 #ifdef CONFIG_SMP
-#define STOP_SCHED_CLASS	*(__stop_sched_class)
+#define STOP_SCHED_CLASS		\
+	STRUCT_ALIGN();			\
+	sched_class_highest = .;	\
+	*(__stop_sched_class)
+#define BEFORE_DL_SCHED_CLASS
 #else
 #define STOP_SCHED_CLASS
+#define BEFORE_DL_SCHED_CLASS		\
+	STRUCT_ALIGN();			\
+	sched_class_highest = .;
 #endif
 
 /*
@@ -120,9 +127,11 @@
  * relation to each other.
  */
 #define SCHED_DATA				\
+	STRUCT_ALIGN();				\
 	*(__idle_sched_class)			\
 	*(__fair_sched_class)			\
 	*(__rt_sched_class)			\
+	BEFORE_DL_SCHED_CLASS			\
 	*(__dl_sched_class)			\
 	STOP_SCHED_CLASS
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 280a3c735935..0554c588ad85 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1771,17 +1771,14 @@ static inline void set_next_task(struct rq *rq, struct task_struct *next)
 	next->sched_class->set_next_task(rq, next, false);
 }
 
-#ifdef CONFIG_SMP
-#define sched_class_highest (&stop_sched_class)
-#else
-#define sched_class_highest (&dl_sched_class)
-#endif
+/* Defined in include/asm-generic/vmlinux.lds.h */
+extern struct sched_class sched_class_highest;
 
 #define for_class_range(class, _from, _to) \
 	for (class = (_from); class != (_to); class = class->next)
 
 #define for_each_class(class) \
-	for_class_range(class, sched_class_highest, NULL)
+	for_class_range(class, &sched_class_highest, NULL)
 
 extern const struct sched_class stop_sched_class;
 extern const struct sched_class dl_sched_class;
-- 
2.24.0



  parent reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-19 21:44 [RFC][PATCH 0/4] sched: Optimizations to sched_class processing Steven Rostedt
2019-12-19 21:44 ` [RFC][PATCH 1/4] sched: Force the address order of each sched class descriptor Steven Rostedt
2019-12-20  8:52   ` Rasmus Villemoes
2019-12-20 10:00     ` Peter Zijlstra
2019-12-20 10:12       ` Rasmus Villemoes
2019-12-20 10:44         ` Kirill Tkhai
2019-12-20 15:18           ` Steven Rostedt
2019-12-20 12:19         ` Peter Zijlstra
2019-12-20 14:34           ` Rasmus Villemoes
2019-12-19 21:44 ` Steven Rostedt [this message]
2019-12-20  8:52   ` [RFC][PATCH 2/4] sched: Have sched_class_highest define by vmlinux.lds.h Rasmus Villemoes
2020-06-25 11:53   ` [tip: sched/core] " tip-bot2 for Steven Rostedt (VMware)
2019-12-19 21:44 ` [RFC][PATCH 3/4] sched: Remove struct sched_class next field Steven Rostedt
2019-12-20 12:14   ` Rasmus Villemoes
2020-06-25 11:53   ` [tip: sched/core] sched: Remove struct sched_class::next field tip-bot2 for Steven Rostedt (VMware)
2019-12-19 21:44 ` [RFC][PATCH 4/4] sched: Micro optimization in pick_next_task() and in check_preempt_curr() Steven Rostedt

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