From: Sven-Thorsten Dietrich <sdietrich@xxxxxxxxxx>
Add /proc/sys/kernel/lateral_steal, to allow switching on and off
equal-priority mutex stealing between threads.
Signed-off-by: Sven-Thorsten Dietrich <sdietrich@xxxxxxx>
---
kernel/rtmutex.c | 8 ++++++--
kernel/sysctl.c | 14 ++++++++++++++
2 files changed, 20 insertions(+), 2 deletions(-)
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index da077e5..62e7af5 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -27,6 +27,9 @@ int rtlock_timeout __read_mostly = CONFIG_RTLOCK_DELAY;
#ifdef CONFIG_ADAPTIVE_RTMUTEX
int rtmutex_timeout __read_mostly = CONFIG_RTMUTEX_DELAY;
#endif
+#ifdef CONFIG_RTLOCK_LATERAL_STEAL
+int rtmutex_lateral_steal __read_mostly = 1;
+#endif
/*
* lock->owner state tracking:
@@ -331,7 +334,8 @@ static inline int lock_is_stealable(struct task_struct *pendowner, int unfair)
if (current->prio > pendowner->prio)
return 0;
- if (!unfair && (current->prio == pendowner->prio))
+ if (unlikely(current->prio == pendowner->prio) &&
+ !(unfair && rtmutex_lateral_steal))
#endif
return 0;
@@ -355,7 +359,7 @@ static inline int try_to_steal_lock(struct rt_mutex *lock, int unfair)
return 1;
spin_lock(&pendowner->pi_lock);
- if (!lock_is_stealable(pendowner, unfair)) {
+ if (!lock_is_stealable(pendowner, (unfair & rtmutex_lateral_steal))) {
spin_unlock(&pendowner->pi_lock);
return 0;
}
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 3465af2..c1a1c6d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -179,6 +179,10 @@ extern struct ctl_table inotify_table[];
int sysctl_legacy_va_layout;
#endif
+#ifdef CONFIG_RTLOCK_LATERAL_STEAL
+extern int rtmutex_lateral_steal;
+#endif
+
extern int prove_locking;
extern int lock_stat;
@@ -986,6 +990,16 @@ static struct ctl_table kern_table[] = {
.proc_handler = &proc_dointvec,
},
#endif
+#ifdef CONFIG_RTLOCK_LATERAL_STEAL
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "rtmutex_lateral_steal",
+ .data = &rtmutex_lateral_steal,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = &proc_dointvec,
+ },
+#endif
#ifdef CONFIG_PROC_FS
{
.ctl_name = CTL_UNNUMBERED,
-
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
