2022-10-19 23:47:29

by Zqiang

Subject: [PATCH v2] rcu: Make call_rcu() lazy only when CONFIG_RCU_LAZY is enabled

Currently, regardless of whether the CONFIG_RCU_LAZY is enabled,
invoke the call_rcu() is always lazy, it also means that when
CONFIG_RCU_LAZY is disabled, invoke the call_rcu_flush() is also
lazy. therefore, this commit make call_rcu() lazy only when
CONFIG_RCU_LAZY is enabled.

Signed-off-by: Zqiang <[email protected]>
---
v1->v2:
Use IS_ENABLED(CONFIG_RCU_LAZY) to the existing function of the same name.

kernel/rcu/tree.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index abc615808b6e..ecf42b0d3726 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2887,7 +2887,10 @@ EXPORT_SYMBOL_GPL(call_rcu_flush);
*/
void call_rcu(struct rcu_head *head, rcu_callback_t func)
{
- return __call_rcu_common(head, func, true);
+ if (IS_ENABLED(CONFIG_RCU_LAZY))
+ return __call_rcu_common(head, func, true);
+ else
+ return __call_rcu_common(head, func, false);
}
EXPORT_SYMBOL_GPL(call_rcu);

--
2.25.1

2022-10-20 00:05:05

by Paul E. McKenney

Subject: Re: [PATCH v2] rcu: Make call_rcu() lazy only when CONFIG_RCU_LAZY is enabled

On Thu, Oct 20, 2022 at 07:38:35AM +0800, Zqiang wrote:
> Currently, regardless of whether the CONFIG_RCU_LAZY is enabled,
> invoke the call_rcu() is always lazy, it also means that when
> CONFIG_RCU_LAZY is disabled, invoke the call_rcu_flush() is also
> lazy. therefore, this commit make call_rcu() lazy only when
> CONFIG_RCU_LAZY is enabled.
>
> Signed-off-by: Zqiang <[email protected]>
> ---
> v1->v2:
> Use IS_ENABLED(CONFIG_RCU_LAZY) to the existing function of the same name.
>
> kernel/rcu/tree.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index abc615808b6e..ecf42b0d3726 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -2887,7 +2887,10 @@ EXPORT_SYMBOL_GPL(call_rcu_flush);
> */
> void call_rcu(struct rcu_head *head, rcu_callback_t func)
> {
> - return __call_rcu_common(head, func, true);
> + if (IS_ENABLED(CONFIG_RCU_LAZY))
> + return __call_rcu_common(head, func, true);
> + else
> + return __call_rcu_common(head, func, false);

This is much better, but why not something like this?

return __call_rcu_common(head, func, IS_ENABLED(CONFIG_RCU_LAZY));

Thanx, Paul

> }
> EXPORT_SYMBOL_GPL(call_rcu);
>
> --
> 2.25.1
>

2022-10-20 01:01:24

by Zqiang

Subject: RE: [PATCH v2] rcu: Make call_rcu() lazy only when CONFIG_RCU_LAZY is enabled

On Thu, Oct 20, 2022 at 07:38:35AM +0800, Zqiang wrote:
> Currently, regardless of whether the CONFIG_RCU_LAZY is enabled,
> invoke the call_rcu() is always lazy, it also means that when
> CONFIG_RCU_LAZY is disabled, invoke the call_rcu_flush() is also
> lazy. therefore, this commit make call_rcu() lazy only when
> CONFIG_RCU_LAZY is enabled.
>
> Signed-off-by: Zqiang <[email protected]>
> ---
> v1->v2:
> Use IS_ENABLED(CONFIG_RCU_LAZY) to the existing function of the same name.
>
> kernel/rcu/tree.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index abc615808b6e..ecf42b0d3726 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -2887,7 +2887,10 @@ EXPORT_SYMBOL_GPL(call_rcu_flush);
> */
> void call_rcu(struct rcu_head *head, rcu_callback_t func)
> {
> - return __call_rcu_common(head, func, true);
> + if (IS_ENABLED(CONFIG_RCU_LAZY))
> + return __call_rcu_common(head, func, true);
> + else
> + return __call_rcu_common(head, func, false);

>
>This is much better, but why not something like this?

Yes, it looks better, ????.

>
> return __call_rcu_common(head, func, IS_ENABLED(CONFIG_RCU_LAZY));
>
> Thanx, Paul

> }
> EXPORT_SYMBOL_GPL(call_rcu);
>
> --
> 2.25.1
>