From: Sven Dietrich <sdietrich@xxxxxxxxxx>
Signed-off-by: Sven Dietrich <sdietrich@xxxxxxxxxx>
---
kernel/Kconfig.preempt | 11 +++++++++++
kernel/rtmutex.c | 4 ++++
kernel/rtmutex_adaptive.h | 11 +++++++++--
kernel/sysctl.c | 12 ++++++++++++
4 files changed, 36 insertions(+), 2 deletions(-)
diff --git a/kernel/Kconfig.preempt b/kernel/Kconfig.preempt
index 6568519..eebec19 100644
--- a/kernel/Kconfig.preempt
+++ b/kernel/Kconfig.preempt
@@ -212,6 +212,17 @@ config ADAPTIVE_RTLOCK
If unsure, say Y
+config RTLOCK_DELAY
+ int "Default delay (in loops) for adaptive rtlocks"
+ range 0 1000000000
+ depends on ADAPTIVE_RTLOCK
+ default "10000"
+ help
+ This allows you to specify the maximum attempts a task will spin
+ attempting to acquire an rtlock before sleeping. The value is
+ tunable at runtime via a sysctl. A setting of 0 (zero) disables
+ the adaptive algorithm entirely.
+
config SPINLOCK_BKL
bool "Old-Style Big Kernel Lock"
depends on (PREEMPT || SMP) && !PREEMPT_RT
diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index feb938f..4a7423f 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -20,6 +20,10 @@
#include "rtmutex_common.h"
#include "rtmutex_adaptive.h"
+#ifdef CONFIG_ADAPTIVE_RTLOCK
+int rtlock_timeout __read_mostly = CONFIG_RTLOCK_DELAY;
+#endif
+
/*
* lock->owner state tracking:
*
diff --git a/kernel/rtmutex_adaptive.h b/kernel/rtmutex_adaptive.h
index 505fed5..b7e282b 100644
--- a/kernel/rtmutex_adaptive.h
+++ b/kernel/rtmutex_adaptive.h
@@ -39,6 +39,7 @@
#ifdef CONFIG_ADAPTIVE_RTLOCK
struct adaptive_waiter {
struct task_struct *owner;
+ int timeout;
};
/*
@@ -60,7 +61,7 @@ adaptive_wait(struct rt_mutex *lock, struct rt_mutex_waiter *waiter,
{
int sleep = 0;
- for (;;) {
+ for (; adaptive->timeout > 0; adaptive->timeout--) {
/*
* If the task was re-awoken, break out completely so we can
* reloop through the lock-acquisition code.
@@ -101,6 +102,9 @@ adaptive_wait(struct rt_mutex *lock, struct rt_mutex_waiter *waiter,
cpu_relax();
}
+ if (adaptive->timeout <= 0)
+ sleep = 1;
+
put_task_struct(adaptive->owner);
return sleep;
@@ -118,8 +122,11 @@ prepare_adaptive_wait(struct rt_mutex *lock, struct adaptive_waiter *adaptive)
get_task_struct(adaptive->owner);
}
+extern int rtlock_timeout;
+
#define DECLARE_ADAPTIVE_WAITER(name) \
- struct adaptive_waiter name = { .owner = NULL, }
+ struct adaptive_waiter name = { .owner = NULL, \
+ .timeout = rtlock_timeout, }
#else
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 541aa9f..36259e4 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -58,6 +58,8 @@
#include <asm/stacktrace.h>
#endif
+#include "rtmutex_adaptive.h"
+
static int deprecated_sysctl_warning(struct __sysctl_args *args);
#if defined(CONFIG_SYSCTL)
@@ -964,6 +966,16 @@ static struct ctl_table kern_table[] = {
.proc_handler = &proc_dointvec,
},
#endif
+#ifdef CONFIG_ADAPTIVE_RTLOCK
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "rtlock_timeout",
+ .data = &rtlock_timeout,
+ .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
