[PATCH 1/2] smpboot, idle: Optimize calls to smp_processor_id() in idle_threads_init()

[PATCH 1/2] smpboot, idle: Optimize calls to smp_processor_id() in idle_threads_init()

[Srivatsa S. Bhat]

While trying to initialize idle threads for all cpus, idle_threads_init()
calls smp_processor_id() in a loop, which is unnecessary. The intent
is to initialize idle threads for all non-boot cpus. So just use a variable
to note the boot cpu and use it in the loop.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

 kernel/smpboot.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index e1a797e..0f2162f 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -52,10 +52,12 @@ static inline void idle_init(unsigned int cpu)
  */
 void __init idle_threads_init(void)
 {
-	unsigned int cpu;
+	unsigned int cpu, boot_cpu;
+
+	boot_cpu = smp_processor_id();
 
 	for_each_possible_cpu(cpu) {
-		if (cpu != smp_processor_id())
+		if (cpu != boot_cpu)
 			idle_init(cpu);
 	}
 }

[PATCH 2/2] smpboot, idle: Fix comment mismatch over idle_threads_init()

[Srivatsa S. Bhat]

The comment over idle_threads_init() really talks about the functionality
of idle_init(). Move that comment to idle_init(), and add a suitable
comment over idle_threads_init().

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
---

 kernel/smpboot.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index 0f2162f..98f60c5 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -31,6 +31,12 @@ void __init idle_thread_set_boot_cpu(void)
 	per_cpu(idle_threads, smp_processor_id()) = current;
 }
 
+/**
+ * idle_init - Initialize the idle thread for a cpu
+ * @cpu:	The cpu for which the idle thread should be initialized
+ *
+ * Creates the thread if it does not exist.
+ */
 static inline void idle_init(unsigned int cpu)
 {
 	struct task_struct *tsk = per_cpu(idle_threads, cpu);
@@ -45,10 +51,7 @@ static inline void idle_init(unsigned int cpu)
 }
 
 /**
- * idle_thread_init - Initialize the idle thread for a cpu
- * @cpu:	The cpu for which the idle thread should be initialized
- *
- * Creates the thread if it does not exist.
+ * idle_threads_init - Initialize idle threads for all cpus
  */
 void __init idle_threads_init(void)
 {

[tip:smp/hotplug] smpboot, idle: Fix comment mismatch over idle_threads_init()

[tip-bot for Srivatsa S. Bhat]

Commit-ID:  4a70d2d9909b43ed88043b98cabe2c7fbd563021
Gitweb:     http://git.kernel.org/tip/4a70d2d9909b43ed88043b98cabe2c7fbd563021
Author:     Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
AuthorDate: Thu, 24 May 2012 20:41:00 +0530
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 24 May 2012 22:58:08 +0200

smpboot, idle: Fix comment mismatch over idle_threads_init()

The comment over idle_threads_init() really talks about the functionality
of idle_init(). Move that comment to idle_init(), and add a suitable
comment over idle_threads_init().

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: suresh.b.siddha@intel.com
Cc: venki@google.com
Cc: nikunj@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/20120524151100.2549.66501.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/smpboot.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index 0f2162f..98f60c5 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -31,6 +31,12 @@ void __init idle_thread_set_boot_cpu(void)
 	per_cpu(idle_threads, smp_processor_id()) = current;
 }
 
+/**
+ * idle_init - Initialize the idle thread for a cpu
+ * @cpu:	The cpu for which the idle thread should be initialized
+ *
+ * Creates the thread if it does not exist.
+ */
 static inline void idle_init(unsigned int cpu)
 {
 	struct task_struct *tsk = per_cpu(idle_threads, cpu);
@@ -45,10 +51,7 @@ static inline void idle_init(unsigned int cpu)
 }
 
 /**
- * idle_thread_init - Initialize the idle thread for a cpu
- * @cpu:	The cpu for which the idle thread should be initialized
- *
- * Creates the thread if it does not exist.
+ * idle_threads_init - Initialize idle threads for all cpus
  */
 void __init idle_threads_init(void)
 {

[tip:smp/hotplug] smpboot, idle: Optimize calls to smp_processor_id() in idle_threads_init()

[tip-bot for Srivatsa S. Bhat]

Commit-ID:  ee74d13229fb606353ff56f4927fa93b37e95bbe
Gitweb:     http://git.kernel.org/tip/ee74d13229fb606353ff56f4927fa93b37e95bbe
Author:     Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
AuthorDate: Thu, 24 May 2012 20:40:55 +0530
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 24 May 2012 22:58:08 +0200

smpboot, idle: Optimize calls to smp_processor_id() in idle_threads_init()

While trying to initialize idle threads for all cpus, idle_threads_init()
calls smp_processor_id() in a loop, which is unnecessary. The intent
is to initialize idle threads for all non-boot cpus. So just use a variable
to note the boot cpu and use it in the loop.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: suresh.b.siddha@intel.com
Cc: venki@google.com
Cc: nikunj@linux.vnet.ibm.com
Link: http://lkml.kernel.org/r/20120524151055.2549.64309.stgit@srivatsabhat.in.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/smpboot.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index e1a797e..0f2162f 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -52,10 +52,12 @@ static inline void idle_init(unsigned int cpu)
  */
 void __init idle_threads_init(void)
 {
-	unsigned int cpu;
+	unsigned int cpu, boot_cpu;
+
+	boot_cpu = smp_processor_id();
 
 	for_each_possible_cpu(cpu) {
-		if (cpu != smp_processor_id())
+		if (cpu != boot_cpu)
 			idle_init(cpu);
 	}
 }