timers: /proc/sys sysctl hook to enable timer migration

* Arun R Bharadwaj <arun@linux.vnet.ibm.com> [2009-04-16 12:11:36]:

This patch creates the /proc/sys sysctl interface at
/proc/sys/kernel/timer_migration

Timer migration is enabled by default.

To disable timer migration, when CONFIG_SCHED_DEBUG = y,

echo 0 > /proc/sys/kernel/timer_migration

Signed-off-by: Arun R Bharadwaj <arun@linux.vnet.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/sched.h b/include/linux/sched.h
index b4c38bc8049cbbea17e0ca4f929f35df9cddbe1f..618504010400203eb61b05965ea03cec9f148a9b 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1766,6 +1766,7 @@ extern unsigned int sysctl_sched_child_runs_first;
 extern unsigned int sysctl_sched_features;
 extern unsigned int sysctl_sched_migration_cost;
 extern unsigned int sysctl_sched_nr_migrate;
+extern unsigned int sysctl_timer_migration;
 
 int sched_nr_latency_handler(struct ctl_table *table, int write,
                struct file *file, void __user *buffer, size_t *length,

diff --git a/kernel/sched.c b/kernel/sched.c
index 9c5b4d3f97ab2b1e9e0e6fee62887198f907eb4d..7f1dd56af863bd291d0ca2e39e81d0dd94b910d0 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -8731,6 +8731,8 @@ void __init sched_init_smp(void)
 }
 #endif /* CONFIG_SMP */
 
+const_debug unsigned int sysctl_timer_migration = 1;
+
 int in_sched_functions(unsigned long addr)
 {
        return in_lock_functions(addr) ||

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index e3d2c7dd59b9791ad14c8b48e5fb804a38052ac8..b3ce581373030db501d83ea08c4a771f0a02aeae 100644 (file)
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -324,6 +324,14 @@ static struct ctl_table kern_table[] = {
                .mode           = 0644,
                .proc_handler   = &proc_dointvec,
        },
+       {
+               .ctl_name       = CTL_UNNUMBERED,
+               .procname       = "timer_migration",
+               .data           = &sysctl_timer_migration,
+               .maxlen         = sizeof(unsigned int),
+               .mode           = 0644,
+               .proc_handler   = &proc_dointvec,
+       },
 #endif
        {
                .ctl_name       = CTL_UNNUMBERED,