* [PATCH 1/2 v2] rcu,cleanup: move synchronize_sched_expedited() out of sched.c
@ 2010-10-20 6:12 Lai Jiangshan
2010-10-20 19:15 ` Paul E. McKenney
0 siblings, 1 reply; 6+ messages in thread
From: Lai Jiangshan @ 2010-10-20 6:12 UTC (permalink / raw)
To: Paul E. McKenney, Ingo Molnar, LKML
The first version of synchronize_sched_expedited() use the migration code
of the scheduler code, so it have to be implemented in sched.c
but now, the synchronize_sched_expedited() does not use such code,
it is time to move it out of sched.c.
Different rcu implementation' synchronize_sched_expedited() are also
different. so we move synchronize_sched_expedited() to kernel/rcutree_plugin.h
or include/linux/rcutiny.h instead of kerenl/rcupdate.c
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
include/linux/rcupdate.h | 1
include/linux/rcutiny.h | 5 +++
include/linux/rcutree.h | 1
kernel/rcutree_plugin.h | 71 +++++++++++++++++++++++++++++++++++++++++++++++
kernel/sched.c | 69 ---------------------------------------------
5 files changed, 77 insertions(+), 70 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 0d0b640..ead36da 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -66,7 +66,6 @@ extern void call_rcu_sched(struct rcu_head *head,
extern void synchronize_sched(void);
extern void rcu_barrier_bh(void);
extern void rcu_barrier_sched(void);
-extern void synchronize_sched_expedited(void);
extern int sched_expedited_torture_stats(char *page);
static inline void __rcu_read_lock_bh(void)
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 13877cb..4d84452 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -58,6 +58,11 @@ static inline void synchronize_rcu_bh_expedited(void)
synchronize_sched();
}
+static inline void synchronize_sched_expedited(void)
+{
+ synchronize_sched();
+}
+
#ifdef CONFIG_TINY_RCU
static inline void rcu_preempt_note_context_switch(void)
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 95518e6..9a1fd6c 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -47,6 +47,7 @@ static inline void exit_rcu(void)
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
extern void synchronize_rcu_bh(void);
+extern void synchronize_sched_expedited(void);
extern void synchronize_rcu_expedited(void);
static inline void synchronize_rcu_bh_expedited(void)
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 0e75d60..1f4cb21 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -25,6 +25,7 @@
*/
#include <linux/delay.h>
+#include <linux/stop_machine.h>
/*
* Check the RCU kernel configuration parameters and print informative
@@ -581,6 +582,76 @@ void synchronize_rcu(void)
}
EXPORT_SYMBOL_GPL(synchronize_rcu);
+#ifndef CONFIG_SMP
+
+void synchronize_sched_expedited(void)
+{
+ cond_resched();
+}
+EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
+
+#else /* #ifndef CONFIG_SMP */
+
+static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
+
+static int synchronize_sched_expedited_cpu_stop(void *data)
+{
+ /*
+ * There must be a full memory barrier on each affected CPU
+ * between the time that try_stop_cpus() is called and the
+ * time that it returns.
+ *
+ * In the current initial implementation of cpu_stop, the
+ * above condition is already met when the control reaches
+ * this point and the following smp_mb() is not strictly
+ * necessary. Do smp_mb() anyway for documentation and
+ * robustness against future implementation changes.
+ */
+ smp_mb(); /* See above comment block. */
+ return 0;
+}
+
+/*
+ * Wait for an rcu-sched grace period to elapse, but use "big hammer"
+ * approach to force grace period to end quickly. This consumes
+ * significant time on all CPUs, and is thus not recommended for
+ * any sort of common-case code.
+ *
+ * Note that it is illegal to call this function while holding any
+ * lock that is acquired by a CPU-hotplug notifier. Failing to
+ * observe this restriction will result in deadlock.
+ */
+void synchronize_sched_expedited(void)
+{
+ int snap, trycount = 0;
+
+ smp_mb(); /* ensure prior mod happens before capturing snap. */
+ snap = atomic_read(&synchronize_sched_expedited_count) + 1;
+ get_online_cpus();
+ while (try_stop_cpus(cpu_online_mask,
+ synchronize_sched_expedited_cpu_stop,
+ NULL) == -EAGAIN) {
+ put_online_cpus();
+ if (trycount++ < 10)
+ udelay(trycount * num_online_cpus());
+ else {
+ synchronize_sched();
+ return;
+ }
+ if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
+ smp_mb(); /* ensure test happens before caller kfree */
+ return;
+ }
+ get_online_cpus();
+ }
+ atomic_inc(&synchronize_sched_expedited_count);
+ smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
+ put_online_cpus();
+}
+EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
+
+#endif /* #else #ifndef CONFIG_SMP */
+
static DECLARE_WAIT_QUEUE_HEAD(sync_rcu_preempt_exp_wq);
static long sync_rcu_preempt_exp_count;
static DEFINE_MUTEX(sync_rcu_preempt_exp_mutex);
diff --git a/kernel/sched.c b/kernel/sched.c
index abf8440..9dc7775 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -9332,72 +9332,3 @@ struct cgroup_subsys cpuacct_subsys = {
};
#endif /* CONFIG_CGROUP_CPUACCT */
-#ifndef CONFIG_SMP
-
-void synchronize_sched_expedited(void)
-{
- barrier();
-}
-EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
-
-#else /* #ifndef CONFIG_SMP */
-
-static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
-
-static int synchronize_sched_expedited_cpu_stop(void *data)
-{
- /*
- * There must be a full memory barrier on each affected CPU
- * between the time that try_stop_cpus() is called and the
- * time that it returns.
- *
- * In the current initial implementation of cpu_stop, the
- * above condition is already met when the control reaches
- * this point and the following smp_mb() is not strictly
- * necessary. Do smp_mb() anyway for documentation and
- * robustness against future implementation changes.
- */
- smp_mb(); /* See above comment block. */
- return 0;
-}
-
-/*
- * Wait for an rcu-sched grace period to elapse, but use "big hammer"
- * approach to force grace period to end quickly. This consumes
- * significant time on all CPUs, and is thus not recommended for
- * any sort of common-case code.
- *
- * Note that it is illegal to call this function while holding any
- * lock that is acquired by a CPU-hotplug notifier. Failing to
- * observe this restriction will result in deadlock.
- */
-void synchronize_sched_expedited(void)
-{
- int snap, trycount = 0;
-
- smp_mb(); /* ensure prior mod happens before capturing snap. */
- snap = atomic_read(&synchronize_sched_expedited_count) + 1;
- get_online_cpus();
- while (try_stop_cpus(cpu_online_mask,
- synchronize_sched_expedited_cpu_stop,
- NULL) == -EAGAIN) {
- put_online_cpus();
- if (trycount++ < 10)
- udelay(trycount * num_online_cpus());
- else {
- synchronize_sched();
- return;
- }
- if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
- smp_mb(); /* ensure test happens before caller kfree */
- return;
- }
- get_online_cpus();
- }
- atomic_inc(&synchronize_sched_expedited_count);
- smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
- put_online_cpus();
-}
-EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
-
-#endif /* #else #ifndef CONFIG_SMP */
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2 v2] rcu,cleanup: move synchronize_sched_expedited() out of sched.c
2010-10-20 6:12 [PATCH 1/2 v2] rcu,cleanup: move synchronize_sched_expedited() out of sched.c Lai Jiangshan
@ 2010-10-20 19:15 ` Paul E. McKenney
2010-10-21 0:19 ` Paul E. McKenney
0 siblings, 1 reply; 6+ messages in thread
From: Paul E. McKenney @ 2010-10-20 19:15 UTC (permalink / raw)
To: Lai Jiangshan; +Cc: Ingo Molnar, LKML
On Wed, Oct 20, 2010 at 02:12:58PM +0800, Lai Jiangshan wrote:
> The first version of synchronize_sched_expedited() use the migration code
> of the scheduler code, so it have to be implemented in sched.c
>
> but now, the synchronize_sched_expedited() does not use such code,
> it is time to move it out of sched.c.
>
> Different rcu implementation' synchronize_sched_expedited() are also
> different. so we move synchronize_sched_expedited() to kernel/rcutree_plugin.h
> or include/linux/rcutiny.h instead of kerenl/rcupdate.c
Queued, thank you!!!
Thanx, Paul
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
> include/linux/rcupdate.h | 1
> include/linux/rcutiny.h | 5 +++
> include/linux/rcutree.h | 1
> kernel/rcutree_plugin.h | 71 +++++++++++++++++++++++++++++++++++++++++++++++
> kernel/sched.c | 69 ---------------------------------------------
> 5 files changed, 77 insertions(+), 70 deletions(-)
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index 0d0b640..ead36da 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -66,7 +66,6 @@ extern void call_rcu_sched(struct rcu_head *head,
> extern void synchronize_sched(void);
> extern void rcu_barrier_bh(void);
> extern void rcu_barrier_sched(void);
> -extern void synchronize_sched_expedited(void);
> extern int sched_expedited_torture_stats(char *page);
>
> static inline void __rcu_read_lock_bh(void)
> diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
> index 13877cb..4d84452 100644
> --- a/include/linux/rcutiny.h
> +++ b/include/linux/rcutiny.h
> @@ -58,6 +58,11 @@ static inline void synchronize_rcu_bh_expedited(void)
> synchronize_sched();
> }
>
> +static inline void synchronize_sched_expedited(void)
> +{
> + synchronize_sched();
> +}
> +
> #ifdef CONFIG_TINY_RCU
>
> static inline void rcu_preempt_note_context_switch(void)
> diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
> index 95518e6..9a1fd6c 100644
> --- a/include/linux/rcutree.h
> +++ b/include/linux/rcutree.h
> @@ -47,6 +47,7 @@ static inline void exit_rcu(void)
> #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
>
> extern void synchronize_rcu_bh(void);
> +extern void synchronize_sched_expedited(void);
> extern void synchronize_rcu_expedited(void);
>
> static inline void synchronize_rcu_bh_expedited(void)
> diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
> index 0e75d60..1f4cb21 100644
> --- a/kernel/rcutree_plugin.h
> +++ b/kernel/rcutree_plugin.h
> @@ -25,6 +25,7 @@
> */
>
> #include <linux/delay.h>
> +#include <linux/stop_machine.h>
>
> /*
> * Check the RCU kernel configuration parameters and print informative
> @@ -581,6 +582,76 @@ void synchronize_rcu(void)
> }
> EXPORT_SYMBOL_GPL(synchronize_rcu);
>
> +#ifndef CONFIG_SMP
> +
> +void synchronize_sched_expedited(void)
> +{
> + cond_resched();
> +}
> +EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> +
> +#else /* #ifndef CONFIG_SMP */
> +
> +static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
> +
> +static int synchronize_sched_expedited_cpu_stop(void *data)
> +{
> + /*
> + * There must be a full memory barrier on each affected CPU
> + * between the time that try_stop_cpus() is called and the
> + * time that it returns.
> + *
> + * In the current initial implementation of cpu_stop, the
> + * above condition is already met when the control reaches
> + * this point and the following smp_mb() is not strictly
> + * necessary. Do smp_mb() anyway for documentation and
> + * robustness against future implementation changes.
> + */
> + smp_mb(); /* See above comment block. */
> + return 0;
> +}
> +
> +/*
> + * Wait for an rcu-sched grace period to elapse, but use "big hammer"
> + * approach to force grace period to end quickly. This consumes
> + * significant time on all CPUs, and is thus not recommended for
> + * any sort of common-case code.
> + *
> + * Note that it is illegal to call this function while holding any
> + * lock that is acquired by a CPU-hotplug notifier. Failing to
> + * observe this restriction will result in deadlock.
> + */
> +void synchronize_sched_expedited(void)
> +{
> + int snap, trycount = 0;
> +
> + smp_mb(); /* ensure prior mod happens before capturing snap. */
> + snap = atomic_read(&synchronize_sched_expedited_count) + 1;
> + get_online_cpus();
> + while (try_stop_cpus(cpu_online_mask,
> + synchronize_sched_expedited_cpu_stop,
> + NULL) == -EAGAIN) {
> + put_online_cpus();
> + if (trycount++ < 10)
> + udelay(trycount * num_online_cpus());
> + else {
> + synchronize_sched();
> + return;
> + }
> + if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
> + smp_mb(); /* ensure test happens before caller kfree */
> + return;
> + }
> + get_online_cpus();
> + }
> + atomic_inc(&synchronize_sched_expedited_count);
> + smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
> + put_online_cpus();
> +}
> +EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> +
> +#endif /* #else #ifndef CONFIG_SMP */
> +
> static DECLARE_WAIT_QUEUE_HEAD(sync_rcu_preempt_exp_wq);
> static long sync_rcu_preempt_exp_count;
> static DEFINE_MUTEX(sync_rcu_preempt_exp_mutex);
> diff --git a/kernel/sched.c b/kernel/sched.c
> index abf8440..9dc7775 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -9332,72 +9332,3 @@ struct cgroup_subsys cpuacct_subsys = {
> };
> #endif /* CONFIG_CGROUP_CPUACCT */
>
> -#ifndef CONFIG_SMP
> -
> -void synchronize_sched_expedited(void)
> -{
> - barrier();
> -}
> -EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> -
> -#else /* #ifndef CONFIG_SMP */
> -
> -static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
> -
> -static int synchronize_sched_expedited_cpu_stop(void *data)
> -{
> - /*
> - * There must be a full memory barrier on each affected CPU
> - * between the time that try_stop_cpus() is called and the
> - * time that it returns.
> - *
> - * In the current initial implementation of cpu_stop, the
> - * above condition is already met when the control reaches
> - * this point and the following smp_mb() is not strictly
> - * necessary. Do smp_mb() anyway for documentation and
> - * robustness against future implementation changes.
> - */
> - smp_mb(); /* See above comment block. */
> - return 0;
> -}
> -
> -/*
> - * Wait for an rcu-sched grace period to elapse, but use "big hammer"
> - * approach to force grace period to end quickly. This consumes
> - * significant time on all CPUs, and is thus not recommended for
> - * any sort of common-case code.
> - *
> - * Note that it is illegal to call this function while holding any
> - * lock that is acquired by a CPU-hotplug notifier. Failing to
> - * observe this restriction will result in deadlock.
> - */
> -void synchronize_sched_expedited(void)
> -{
> - int snap, trycount = 0;
> -
> - smp_mb(); /* ensure prior mod happens before capturing snap. */
> - snap = atomic_read(&synchronize_sched_expedited_count) + 1;
> - get_online_cpus();
> - while (try_stop_cpus(cpu_online_mask,
> - synchronize_sched_expedited_cpu_stop,
> - NULL) == -EAGAIN) {
> - put_online_cpus();
> - if (trycount++ < 10)
> - udelay(trycount * num_online_cpus());
> - else {
> - synchronize_sched();
> - return;
> - }
> - if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
> - smp_mb(); /* ensure test happens before caller kfree */
> - return;
> - }
> - get_online_cpus();
> - }
> - atomic_inc(&synchronize_sched_expedited_count);
> - smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
> - put_online_cpus();
> -}
> -EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> -
> -#endif /* #else #ifndef CONFIG_SMP */
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2 v2] rcu,cleanup: move synchronize_sched_expedited() out of sched.c
2010-10-20 19:15 ` Paul E. McKenney
@ 2010-10-21 0:19 ` Paul E. McKenney
2010-10-21 3:29 ` Lai Jiangshan
0 siblings, 1 reply; 6+ messages in thread
From: Paul E. McKenney @ 2010-10-21 0:19 UTC (permalink / raw)
To: Lai Jiangshan; +Cc: Ingo Molnar, LKML
On Wed, Oct 20, 2010 at 12:15:12PM -0700, Paul E. McKenney wrote:
> On Wed, Oct 20, 2010 at 02:12:58PM +0800, Lai Jiangshan wrote:
> > The first version of synchronize_sched_expedited() use the migration code
> > of the scheduler code, so it have to be implemented in sched.c
> >
> > but now, the synchronize_sched_expedited() does not use such code,
> > it is time to move it out of sched.c.
> >
> > Different rcu implementation' synchronize_sched_expedited() are also
> > different. so we move synchronize_sched_expedited() to kernel/rcutree_plugin.h
> > or include/linux/rcutiny.h instead of kerenl/rcupdate.c
>
> Queued, thank you!!!
Hello again, Lai,
I hit the following build error during testing:
kernel/built-in.o: In function `.synchronize_rcu_expedited':
(.text+0x787d8): undefined reference to `.synchronize_sched_expedited'
kernel/built-in.o:(.toc1+0x1fe0): undefined reference to `synchronize_sched_expedited'
This build uses defconfig with the following applied:
CONFIG_RCU_TRACE=y
CONFIG_RCU_FAST_NO_HZ=y
CONFIG_NO_HZ=y
CONFIG_RCU_CPU_STALL_DETECTOR=y
CONFIG_SMP=y
CONFIG_RCU_FANOUT=8
CONFIG_NR_CPUS=8
CONFIG_RCU_FANOUT_EXACT=n
CONFIG_HOTPLUG_CPU=y
CONFIG_PREEMPT_NONE=y
CONFIG_PREEMPT_VOLUNTARY=n
CONFIG_PREEMPT=n
CONFIG_TREE_RCU=y
CONFIG_TREE_PREEMPT_RCU=n
CONFIG_RCU_TORTURE_TEST=m
CONFIG_MODULE_UNLOAD=y
CONFIG_SYSFS_DEPRECATED_V2=y
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y
Thoughts?
Thanx, Paul
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2 v2] rcu,cleanup: move synchronize_sched_expedited() out of sched.c
2010-10-21 0:19 ` Paul E. McKenney
@ 2010-10-21 3:29 ` Lai Jiangshan
2010-10-21 4:39 ` Paul E. McKenney
0 siblings, 1 reply; 6+ messages in thread
From: Lai Jiangshan @ 2010-10-21 3:29 UTC (permalink / raw)
To: paulmck; +Cc: Ingo Molnar, LKML
On 10/21/2010 08:19 AM, Paul E. McKenney wrote:
> On Wed, Oct 20, 2010 at 12:15:12PM -0700, Paul E. McKenney wrote:
>> On Wed, Oct 20, 2010 at 02:12:58PM +0800, Lai Jiangshan wrote:
>>> The first version of synchronize_sched_expedited() use the migration code
>>> of the scheduler code, so it have to be implemented in sched.c
>>>
>>> but now, the synchronize_sched_expedited() does not use such code,
>>> it is time to move it out of sched.c.
>>>
>>> Different rcu implementation' synchronize_sched_expedited() are also
>>> different. so we move synchronize_sched_expedited() to kernel/rcutree_plugin.h
>>> or include/linux/rcutiny.h instead of kerenl/rcupdate.c
>>
>> Queued, thank you!!!
>
> Hello again, Lai,
>
> I hit the following build error during testing:
>
> kernel/built-in.o: In function `.synchronize_rcu_expedited':
> (.text+0x787d8): undefined reference to `.synchronize_sched_expedited'
> kernel/built-in.o:(.toc1+0x1fe0): undefined reference to `synchronize_sched_expedited'
>
> This build uses defconfig with the following applied:
>
> CONFIG_RCU_TRACE=y
> CONFIG_RCU_FAST_NO_HZ=y
> CONFIG_NO_HZ=y
> CONFIG_RCU_CPU_STALL_DETECTOR=y
> CONFIG_SMP=y
> CONFIG_RCU_FANOUT=8
> CONFIG_NR_CPUS=8
> CONFIG_RCU_FANOUT_EXACT=n
> CONFIG_HOTPLUG_CPU=y
> CONFIG_PREEMPT_NONE=y
> CONFIG_PREEMPT_VOLUNTARY=n
> CONFIG_PREEMPT=n
> CONFIG_TREE_RCU=y
> CONFIG_TREE_PREEMPT_RCU=n
> CONFIG_RCU_TORTURE_TEST=m
> CONFIG_MODULE_UNLOAD=y
> CONFIG_SYSFS_DEPRECATED_V2=y
> CONFIG_IKCONFIG=y
> CONFIG_IKCONFIG_PROC=y
>
> Thoughts?
>
> Thanx, Paul
>
>
I moved the code into CONFIG_TREE_PREEMPT_RCU=y codes. fixed version:
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 0d0b640..ead36da 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -66,7 +66,6 @@ extern void call_rcu_sched(struct rcu_head *head,
extern void synchronize_sched(void);
extern void rcu_barrier_bh(void);
extern void rcu_barrier_sched(void);
-extern void synchronize_sched_expedited(void);
extern int sched_expedited_torture_stats(char *page);
static inline void __rcu_read_lock_bh(void)
diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
index 13877cb..4d84452 100644
--- a/include/linux/rcutiny.h
+++ b/include/linux/rcutiny.h
@@ -58,6 +58,11 @@ static inline void synchronize_rcu_bh_expedited(void)
synchronize_sched();
}
+static inline void synchronize_sched_expedited(void)
+{
+ synchronize_sched();
+}
+
#ifdef CONFIG_TINY_RCU
static inline void rcu_preempt_note_context_switch(void)
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 95518e6..9a1fd6c 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -47,6 +47,7 @@ static inline void exit_rcu(void)
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
extern void synchronize_rcu_bh(void);
+extern void synchronize_sched_expedited(void);
extern void synchronize_rcu_expedited(void);
static inline void synchronize_rcu_bh_expedited(void)
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 0e75d60..0de359b 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -25,6 +25,7 @@
*/
#include <linux/delay.h>
+#include <linux/stop_machine.h>
/*
* Check the RCU kernel configuration parameters and print informative
@@ -1014,6 +1015,76 @@ static void __init __rcu_init_preempt(void)
#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
+#ifndef CONFIG_SMP
+
+void synchronize_sched_expedited(void)
+{
+ cond_resched();
+}
+EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
+
+#else /* #ifndef CONFIG_SMP */
+
+static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
+
+static int synchronize_sched_expedited_cpu_stop(void *data)
+{
+ /*
+ * There must be a full memory barrier on each affected CPU
+ * between the time that try_stop_cpus() is called and the
+ * time that it returns.
+ *
+ * In the current initial implementation of cpu_stop, the
+ * above condition is already met when the control reaches
+ * this point and the following smp_mb() is not strictly
+ * necessary. Do smp_mb() anyway for documentation and
+ * robustness against future implementation changes.
+ */
+ smp_mb(); /* See above comment block. */
+ return 0;
+}
+
+/*
+ * Wait for an rcu-sched grace period to elapse, but use "big hammer"
+ * approach to force grace period to end quickly. This consumes
+ * significant time on all CPUs, and is thus not recommended for
+ * any sort of common-case code.
+ *
+ * Note that it is illegal to call this function while holding any
+ * lock that is acquired by a CPU-hotplug notifier. Failing to
+ * observe this restriction will result in deadlock.
+ */
+void synchronize_sched_expedited(void)
+{
+ int snap, trycount = 0;
+
+ smp_mb(); /* ensure prior mod happens before capturing snap. */
+ snap = atomic_read(&synchronize_sched_expedited_count) + 1;
+ get_online_cpus();
+ while (try_stop_cpus(cpu_online_mask,
+ synchronize_sched_expedited_cpu_stop,
+ NULL) == -EAGAIN) {
+ put_online_cpus();
+ if (trycount++ < 10)
+ udelay(trycount * num_online_cpus());
+ else {
+ synchronize_sched();
+ return;
+ }
+ if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
+ smp_mb(); /* ensure test happens before caller kfree */
+ return;
+ }
+ get_online_cpus();
+ }
+ atomic_inc(&synchronize_sched_expedited_count);
+ smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
+ put_online_cpus();
+}
+EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
+
+#endif /* #else #ifndef CONFIG_SMP */
+
#if !defined(CONFIG_RCU_FAST_NO_HZ)
/*
diff --git a/kernel/sched.c b/kernel/sched.c
index abf8440..9dc7775 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -9332,72 +9332,3 @@ struct cgroup_subsys cpuacct_subsys = {
};
#endif /* CONFIG_CGROUP_CPUACCT */
-#ifndef CONFIG_SMP
-
-void synchronize_sched_expedited(void)
-{
- barrier();
-}
-EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
-
-#else /* #ifndef CONFIG_SMP */
-
-static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
-
-static int synchronize_sched_expedited_cpu_stop(void *data)
-{
- /*
- * There must be a full memory barrier on each affected CPU
- * between the time that try_stop_cpus() is called and the
- * time that it returns.
- *
- * In the current initial implementation of cpu_stop, the
- * above condition is already met when the control reaches
- * this point and the following smp_mb() is not strictly
- * necessary. Do smp_mb() anyway for documentation and
- * robustness against future implementation changes.
- */
- smp_mb(); /* See above comment block. */
- return 0;
-}
-
-/*
- * Wait for an rcu-sched grace period to elapse, but use "big hammer"
- * approach to force grace period to end quickly. This consumes
- * significant time on all CPUs, and is thus not recommended for
- * any sort of common-case code.
- *
- * Note that it is illegal to call this function while holding any
- * lock that is acquired by a CPU-hotplug notifier. Failing to
- * observe this restriction will result in deadlock.
- */
-void synchronize_sched_expedited(void)
-{
- int snap, trycount = 0;
-
- smp_mb(); /* ensure prior mod happens before capturing snap. */
- snap = atomic_read(&synchronize_sched_expedited_count) + 1;
- get_online_cpus();
- while (try_stop_cpus(cpu_online_mask,
- synchronize_sched_expedited_cpu_stop,
- NULL) == -EAGAIN) {
- put_online_cpus();
- if (trycount++ < 10)
- udelay(trycount * num_online_cpus());
- else {
- synchronize_sched();
- return;
- }
- if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
- smp_mb(); /* ensure test happens before caller kfree */
- return;
- }
- get_online_cpus();
- }
- atomic_inc(&synchronize_sched_expedited_count);
- smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
- put_online_cpus();
-}
-EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
-
-#endif /* #else #ifndef CONFIG_SMP */
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2 v2] rcu,cleanup: move synchronize_sched_expedited() out of sched.c
2010-10-21 3:29 ` Lai Jiangshan
@ 2010-10-21 4:39 ` Paul E. McKenney
2010-10-21 16:16 ` Paul E. McKenney
0 siblings, 1 reply; 6+ messages in thread
From: Paul E. McKenney @ 2010-10-21 4:39 UTC (permalink / raw)
To: Lai Jiangshan; +Cc: Ingo Molnar, LKML
On Thu, Oct 21, 2010 at 11:29:05AM +0800, Lai Jiangshan wrote:
> On 10/21/2010 08:19 AM, Paul E. McKenney wrote:
> > On Wed, Oct 20, 2010 at 12:15:12PM -0700, Paul E. McKenney wrote:
> >> On Wed, Oct 20, 2010 at 02:12:58PM +0800, Lai Jiangshan wrote:
> >>> The first version of synchronize_sched_expedited() use the migration code
> >>> of the scheduler code, so it have to be implemented in sched.c
> >>>
> >>> but now, the synchronize_sched_expedited() does not use such code,
> >>> it is time to move it out of sched.c.
> >>>
> >>> Different rcu implementation' synchronize_sched_expedited() are also
> >>> different. so we move synchronize_sched_expedited() to kernel/rcutree_plugin.h
> >>> or include/linux/rcutiny.h instead of kerenl/rcupdate.c
> >>
> >> Queued, thank you!!!
> >
> > Hello again, Lai,
> >
> > I hit the following build error during testing:
> >
> > kernel/built-in.o: In function `.synchronize_rcu_expedited':
> > (.text+0x787d8): undefined reference to `.synchronize_sched_expedited'
> > kernel/built-in.o:(.toc1+0x1fe0): undefined reference to `synchronize_sched_expedited'
> >
> > This build uses defconfig with the following applied:
> >
> > CONFIG_RCU_TRACE=y
> > CONFIG_RCU_FAST_NO_HZ=y
> > CONFIG_NO_HZ=y
> > CONFIG_RCU_CPU_STALL_DETECTOR=y
> > CONFIG_SMP=y
> > CONFIG_RCU_FANOUT=8
> > CONFIG_NR_CPUS=8
> > CONFIG_RCU_FANOUT_EXACT=n
> > CONFIG_HOTPLUG_CPU=y
> > CONFIG_PREEMPT_NONE=y
> > CONFIG_PREEMPT_VOLUNTARY=n
> > CONFIG_PREEMPT=n
> > CONFIG_TREE_RCU=y
> > CONFIG_TREE_PREEMPT_RCU=n
> > CONFIG_RCU_TORTURE_TEST=m
> > CONFIG_MODULE_UNLOAD=y
> > CONFIG_SYSFS_DEPRECATED_V2=y
> > CONFIG_IKCONFIG=y
> > CONFIG_IKCONFIG_PROC=y
> >
> > Thoughts?
> >
> > Thanx, Paul
> >
> >
>
> I moved the code into CONFIG_TREE_PREEMPT_RCU=y codes. fixed version:
Thank you, queued and am retesting.
Thanx, Paul
> Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> ---
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index 0d0b640..ead36da 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -66,7 +66,6 @@ extern void call_rcu_sched(struct rcu_head *head,
> extern void synchronize_sched(void);
> extern void rcu_barrier_bh(void);
> extern void rcu_barrier_sched(void);
> -extern void synchronize_sched_expedited(void);
> extern int sched_expedited_torture_stats(char *page);
>
> static inline void __rcu_read_lock_bh(void)
> diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
> index 13877cb..4d84452 100644
> --- a/include/linux/rcutiny.h
> +++ b/include/linux/rcutiny.h
> @@ -58,6 +58,11 @@ static inline void synchronize_rcu_bh_expedited(void)
> synchronize_sched();
> }
>
> +static inline void synchronize_sched_expedited(void)
> +{
> + synchronize_sched();
> +}
> +
> #ifdef CONFIG_TINY_RCU
>
> static inline void rcu_preempt_note_context_switch(void)
> diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
> index 95518e6..9a1fd6c 100644
> --- a/include/linux/rcutree.h
> +++ b/include/linux/rcutree.h
> @@ -47,6 +47,7 @@ static inline void exit_rcu(void)
> #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
>
> extern void synchronize_rcu_bh(void);
> +extern void synchronize_sched_expedited(void);
> extern void synchronize_rcu_expedited(void);
>
> static inline void synchronize_rcu_bh_expedited(void)
> diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
> index 0e75d60..0de359b 100644
> --- a/kernel/rcutree_plugin.h
> +++ b/kernel/rcutree_plugin.h
> @@ -25,6 +25,7 @@
> */
>
> #include <linux/delay.h>
> +#include <linux/stop_machine.h>
>
> /*
> * Check the RCU kernel configuration parameters and print informative
> @@ -1014,6 +1015,76 @@ static void __init __rcu_init_preempt(void)
>
> #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
>
> +#ifndef CONFIG_SMP
> +
> +void synchronize_sched_expedited(void)
> +{
> + cond_resched();
> +}
> +EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> +
> +#else /* #ifndef CONFIG_SMP */
> +
> +static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
> +
> +static int synchronize_sched_expedited_cpu_stop(void *data)
> +{
> + /*
> + * There must be a full memory barrier on each affected CPU
> + * between the time that try_stop_cpus() is called and the
> + * time that it returns.
> + *
> + * In the current initial implementation of cpu_stop, the
> + * above condition is already met when the control reaches
> + * this point and the following smp_mb() is not strictly
> + * necessary. Do smp_mb() anyway for documentation and
> + * robustness against future implementation changes.
> + */
> + smp_mb(); /* See above comment block. */
> + return 0;
> +}
> +
> +/*
> + * Wait for an rcu-sched grace period to elapse, but use "big hammer"
> + * approach to force grace period to end quickly. This consumes
> + * significant time on all CPUs, and is thus not recommended for
> + * any sort of common-case code.
> + *
> + * Note that it is illegal to call this function while holding any
> + * lock that is acquired by a CPU-hotplug notifier. Failing to
> + * observe this restriction will result in deadlock.
> + */
> +void synchronize_sched_expedited(void)
> +{
> + int snap, trycount = 0;
> +
> + smp_mb(); /* ensure prior mod happens before capturing snap. */
> + snap = atomic_read(&synchronize_sched_expedited_count) + 1;
> + get_online_cpus();
> + while (try_stop_cpus(cpu_online_mask,
> + synchronize_sched_expedited_cpu_stop,
> + NULL) == -EAGAIN) {
> + put_online_cpus();
> + if (trycount++ < 10)
> + udelay(trycount * num_online_cpus());
> + else {
> + synchronize_sched();
> + return;
> + }
> + if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
> + smp_mb(); /* ensure test happens before caller kfree */
> + return;
> + }
> + get_online_cpus();
> + }
> + atomic_inc(&synchronize_sched_expedited_count);
> + smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
> + put_online_cpus();
> +}
> +EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> +
> +#endif /* #else #ifndef CONFIG_SMP */
> +
> #if !defined(CONFIG_RCU_FAST_NO_HZ)
>
> /*
> diff --git a/kernel/sched.c b/kernel/sched.c
> index abf8440..9dc7775 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -9332,72 +9332,3 @@ struct cgroup_subsys cpuacct_subsys = {
> };
> #endif /* CONFIG_CGROUP_CPUACCT */
>
> -#ifndef CONFIG_SMP
> -
> -void synchronize_sched_expedited(void)
> -{
> - barrier();
> -}
> -EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> -
> -#else /* #ifndef CONFIG_SMP */
> -
> -static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
> -
> -static int synchronize_sched_expedited_cpu_stop(void *data)
> -{
> - /*
> - * There must be a full memory barrier on each affected CPU
> - * between the time that try_stop_cpus() is called and the
> - * time that it returns.
> - *
> - * In the current initial implementation of cpu_stop, the
> - * above condition is already met when the control reaches
> - * this point and the following smp_mb() is not strictly
> - * necessary. Do smp_mb() anyway for documentation and
> - * robustness against future implementation changes.
> - */
> - smp_mb(); /* See above comment block. */
> - return 0;
> -}
> -
> -/*
> - * Wait for an rcu-sched grace period to elapse, but use "big hammer"
> - * approach to force grace period to end quickly. This consumes
> - * significant time on all CPUs, and is thus not recommended for
> - * any sort of common-case code.
> - *
> - * Note that it is illegal to call this function while holding any
> - * lock that is acquired by a CPU-hotplug notifier. Failing to
> - * observe this restriction will result in deadlock.
> - */
> -void synchronize_sched_expedited(void)
> -{
> - int snap, trycount = 0;
> -
> - smp_mb(); /* ensure prior mod happens before capturing snap. */
> - snap = atomic_read(&synchronize_sched_expedited_count) + 1;
> - get_online_cpus();
> - while (try_stop_cpus(cpu_online_mask,
> - synchronize_sched_expedited_cpu_stop,
> - NULL) == -EAGAIN) {
> - put_online_cpus();
> - if (trycount++ < 10)
> - udelay(trycount * num_online_cpus());
> - else {
> - synchronize_sched();
> - return;
> - }
> - if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
> - smp_mb(); /* ensure test happens before caller kfree */
> - return;
> - }
> - get_online_cpus();
> - }
> - atomic_inc(&synchronize_sched_expedited_count);
> - smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
> - put_online_cpus();
> -}
> -EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> -
> -#endif /* #else #ifndef CONFIG_SMP */
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH 1/2 v2] rcu,cleanup: move synchronize_sched_expedited() out of sched.c
2010-10-21 4:39 ` Paul E. McKenney
@ 2010-10-21 16:16 ` Paul E. McKenney
0 siblings, 0 replies; 6+ messages in thread
From: Paul E. McKenney @ 2010-10-21 16:16 UTC (permalink / raw)
To: Lai Jiangshan; +Cc: Ingo Molnar, LKML
On Wed, Oct 20, 2010 at 09:39:53PM -0700, Paul E. McKenney wrote:
> On Thu, Oct 21, 2010 at 11:29:05AM +0800, Lai Jiangshan wrote:
> > On 10/21/2010 08:19 AM, Paul E. McKenney wrote:
> > > On Wed, Oct 20, 2010 at 12:15:12PM -0700, Paul E. McKenney wrote:
> > >> On Wed, Oct 20, 2010 at 02:12:58PM +0800, Lai Jiangshan wrote:
> > >>> The first version of synchronize_sched_expedited() use the migration code
> > >>> of the scheduler code, so it have to be implemented in sched.c
> > >>>
> > >>> but now, the synchronize_sched_expedited() does not use such code,
> > >>> it is time to move it out of sched.c.
> > >>>
> > >>> Different rcu implementation' synchronize_sched_expedited() are also
> > >>> different. so we move synchronize_sched_expedited() to kernel/rcutree_plugin.h
> > >>> or include/linux/rcutiny.h instead of kerenl/rcupdate.c
> > >>
> > >> Queued, thank you!!!
> > >
> > > Hello again, Lai,
> > >
> > > I hit the following build error during testing:
> > >
> > > kernel/built-in.o: In function `.synchronize_rcu_expedited':
> > > (.text+0x787d8): undefined reference to `.synchronize_sched_expedited'
> > > kernel/built-in.o:(.toc1+0x1fe0): undefined reference to `synchronize_sched_expedited'
> > >
> > > This build uses defconfig with the following applied:
> > >
> > > CONFIG_RCU_TRACE=y
> > > CONFIG_RCU_FAST_NO_HZ=y
> > > CONFIG_NO_HZ=y
> > > CONFIG_RCU_CPU_STALL_DETECTOR=y
> > > CONFIG_SMP=y
> > > CONFIG_RCU_FANOUT=8
> > > CONFIG_NR_CPUS=8
> > > CONFIG_RCU_FANOUT_EXACT=n
> > > CONFIG_HOTPLUG_CPU=y
> > > CONFIG_PREEMPT_NONE=y
> > > CONFIG_PREEMPT_VOLUNTARY=n
> > > CONFIG_PREEMPT=n
> > > CONFIG_TREE_RCU=y
> > > CONFIG_TREE_PREEMPT_RCU=n
> > > CONFIG_RCU_TORTURE_TEST=m
> > > CONFIG_MODULE_UNLOAD=y
> > > CONFIG_SYSFS_DEPRECATED_V2=y
> > > CONFIG_IKCONFIG=y
> > > CONFIG_IKCONFIG_PROC=y
> > >
> > > Thoughts?
> > >
> > > Thanx, Paul
> > >
> > >
> >
> > I moved the code into CONFIG_TREE_PREEMPT_RCU=y codes. fixed version:
>
> Thank you, queued and am retesting.
And the new version works much better, thank you! Any news on the
cpumask_any() issue?
Thanx, Paul
> > Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
> > ---
> > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> > index 0d0b640..ead36da 100644
> > --- a/include/linux/rcupdate.h
> > +++ b/include/linux/rcupdate.h
> > @@ -66,7 +66,6 @@ extern void call_rcu_sched(struct rcu_head *head,
> > extern void synchronize_sched(void);
> > extern void rcu_barrier_bh(void);
> > extern void rcu_barrier_sched(void);
> > -extern void synchronize_sched_expedited(void);
> > extern int sched_expedited_torture_stats(char *page);
> >
> > static inline void __rcu_read_lock_bh(void)
> > diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h
> > index 13877cb..4d84452 100644
> > --- a/include/linux/rcutiny.h
> > +++ b/include/linux/rcutiny.h
> > @@ -58,6 +58,11 @@ static inline void synchronize_rcu_bh_expedited(void)
> > synchronize_sched();
> > }
> >
> > +static inline void synchronize_sched_expedited(void)
> > +{
> > + synchronize_sched();
> > +}
> > +
> > #ifdef CONFIG_TINY_RCU
> >
> > static inline void rcu_preempt_note_context_switch(void)
> > diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
> > index 95518e6..9a1fd6c 100644
> > --- a/include/linux/rcutree.h
> > +++ b/include/linux/rcutree.h
> > @@ -47,6 +47,7 @@ static inline void exit_rcu(void)
> > #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
> >
> > extern void synchronize_rcu_bh(void);
> > +extern void synchronize_sched_expedited(void);
> > extern void synchronize_rcu_expedited(void);
> >
> > static inline void synchronize_rcu_bh_expedited(void)
> > diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
> > index 0e75d60..0de359b 100644
> > --- a/kernel/rcutree_plugin.h
> > +++ b/kernel/rcutree_plugin.h
> > @@ -25,6 +25,7 @@
> > */
> >
> > #include <linux/delay.h>
> > +#include <linux/stop_machine.h>
> >
> > /*
> > * Check the RCU kernel configuration parameters and print informative
> > @@ -1014,6 +1015,76 @@ static void __init __rcu_init_preempt(void)
> >
> > #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */
> >
> > +#ifndef CONFIG_SMP
> > +
> > +void synchronize_sched_expedited(void)
> > +{
> > + cond_resched();
> > +}
> > +EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> > +
> > +#else /* #ifndef CONFIG_SMP */
> > +
> > +static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
> > +
> > +static int synchronize_sched_expedited_cpu_stop(void *data)
> > +{
> > + /*
> > + * There must be a full memory barrier on each affected CPU
> > + * between the time that try_stop_cpus() is called and the
> > + * time that it returns.
> > + *
> > + * In the current initial implementation of cpu_stop, the
> > + * above condition is already met when the control reaches
> > + * this point and the following smp_mb() is not strictly
> > + * necessary. Do smp_mb() anyway for documentation and
> > + * robustness against future implementation changes.
> > + */
> > + smp_mb(); /* See above comment block. */
> > + return 0;
> > +}
> > +
> > +/*
> > + * Wait for an rcu-sched grace period to elapse, but use "big hammer"
> > + * approach to force grace period to end quickly. This consumes
> > + * significant time on all CPUs, and is thus not recommended for
> > + * any sort of common-case code.
> > + *
> > + * Note that it is illegal to call this function while holding any
> > + * lock that is acquired by a CPU-hotplug notifier. Failing to
> > + * observe this restriction will result in deadlock.
> > + */
> > +void synchronize_sched_expedited(void)
> > +{
> > + int snap, trycount = 0;
> > +
> > + smp_mb(); /* ensure prior mod happens before capturing snap. */
> > + snap = atomic_read(&synchronize_sched_expedited_count) + 1;
> > + get_online_cpus();
> > + while (try_stop_cpus(cpu_online_mask,
> > + synchronize_sched_expedited_cpu_stop,
> > + NULL) == -EAGAIN) {
> > + put_online_cpus();
> > + if (trycount++ < 10)
> > + udelay(trycount * num_online_cpus());
> > + else {
> > + synchronize_sched();
> > + return;
> > + }
> > + if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
> > + smp_mb(); /* ensure test happens before caller kfree */
> > + return;
> > + }
> > + get_online_cpus();
> > + }
> > + atomic_inc(&synchronize_sched_expedited_count);
> > + smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
> > + put_online_cpus();
> > +}
> > +EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> > +
> > +#endif /* #else #ifndef CONFIG_SMP */
> > +
> > #if !defined(CONFIG_RCU_FAST_NO_HZ)
> >
> > /*
> > diff --git a/kernel/sched.c b/kernel/sched.c
> > index abf8440..9dc7775 100644
> > --- a/kernel/sched.c
> > +++ b/kernel/sched.c
> > @@ -9332,72 +9332,3 @@ struct cgroup_subsys cpuacct_subsys = {
> > };
> > #endif /* CONFIG_CGROUP_CPUACCT */
> >
> > -#ifndef CONFIG_SMP
> > -
> > -void synchronize_sched_expedited(void)
> > -{
> > - barrier();
> > -}
> > -EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> > -
> > -#else /* #ifndef CONFIG_SMP */
> > -
> > -static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
> > -
> > -static int synchronize_sched_expedited_cpu_stop(void *data)
> > -{
> > - /*
> > - * There must be a full memory barrier on each affected CPU
> > - * between the time that try_stop_cpus() is called and the
> > - * time that it returns.
> > - *
> > - * In the current initial implementation of cpu_stop, the
> > - * above condition is already met when the control reaches
> > - * this point and the following smp_mb() is not strictly
> > - * necessary. Do smp_mb() anyway for documentation and
> > - * robustness against future implementation changes.
> > - */
> > - smp_mb(); /* See above comment block. */
> > - return 0;
> > -}
> > -
> > -/*
> > - * Wait for an rcu-sched grace period to elapse, but use "big hammer"
> > - * approach to force grace period to end quickly. This consumes
> > - * significant time on all CPUs, and is thus not recommended for
> > - * any sort of common-case code.
> > - *
> > - * Note that it is illegal to call this function while holding any
> > - * lock that is acquired by a CPU-hotplug notifier. Failing to
> > - * observe this restriction will result in deadlock.
> > - */
> > -void synchronize_sched_expedited(void)
> > -{
> > - int snap, trycount = 0;
> > -
> > - smp_mb(); /* ensure prior mod happens before capturing snap. */
> > - snap = atomic_read(&synchronize_sched_expedited_count) + 1;
> > - get_online_cpus();
> > - while (try_stop_cpus(cpu_online_mask,
> > - synchronize_sched_expedited_cpu_stop,
> > - NULL) == -EAGAIN) {
> > - put_online_cpus();
> > - if (trycount++ < 10)
> > - udelay(trycount * num_online_cpus());
> > - else {
> > - synchronize_sched();
> > - return;
> > - }
> > - if (atomic_read(&synchronize_sched_expedited_count) - snap > 0) {
> > - smp_mb(); /* ensure test happens before caller kfree */
> > - return;
> > - }
> > - get_online_cpus();
> > - }
> > - atomic_inc(&synchronize_sched_expedited_count);
> > - smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
> > - put_online_cpus();
> > -}
> > -EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
> > -
> > -#endif /* #else #ifndef CONFIG_SMP */
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> > Please read the FAQ at http://www.tux.org/lkml/
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2010-10-21 16:16 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-10-20 6:12 [PATCH 1/2 v2] rcu,cleanup: move synchronize_sched_expedited() out of sched.c Lai Jiangshan
2010-10-20 19:15 ` Paul E. McKenney
2010-10-21 0:19 ` Paul E. McKenney
2010-10-21 3:29 ` Lai Jiangshan
2010-10-21 4:39 ` Paul E. McKenney
2010-10-21 16:16 ` Paul E. McKenney
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox