Unverified Commit 41e2d9f3 authored by openeuler-ci-bot's avatar openeuler-ci-bot Committed by Gitee
Browse files

!14321 [OLK-6.6] rcu: Provide a boot time parameter to control lazy RCU 

Merge Pull Request from: @koishimind 
 
Issue:
https://gitee.com/openeuler/kernel/issues/IBE3AN
Commit:
rcu: Provide a boot time parameter to control lazy RCU
rcu/tree: Remove superfluous return from void call_rcu* functions
 
 
Link:https://gitee.com/openeuler/kernel/pulls/14321

 

Reviewed-by: default avatarXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: default avatarZhang Peng <zhangpeng362@huawei.com>
parents 32c34054 62153417

Documentation/admin-guide/kernel-parameters.txt

+5 −0
Original line number Diff line number Diff line
@@ -5073,6 +5073,11 @@ 
			this kernel boot parameter, forcibly setting it

			to zero.



	rcutree.enable_rcu_lazy= [KNL]

			To save power, batch RCU callbacks and flush after

			delay, memory pressure or callback list growing too

			big.



	rcuscale.gp_async= [KNL]

			Measure performance of asynchronous

			grace-period primitives such as call_rcu().

kernel/rcu/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -314,6 +314,19 @@ config RCU_LAZY 
	  To save power, batch RCU callbacks and flush after delay, memory

	  pressure, or callback list growing too big.



	  Requires rcu_nocbs=all to be set.



	  Use rcutree.enable_rcu_lazy=0 to turn it off at boot time.



config RCU_LAZY_DEFAULT_OFF

	bool "Turn RCU lazy invocation off by default"

	depends on RCU_LAZY

	default n

	help

	  Allows building the kernel with CONFIG_RCU_LAZY=y yet keep it default

	  off. Boot time param rcutree.enable_rcu_lazy=1 can be used to switch

	  it back on.



config RCU_DOUBLE_CHECK_CB_TIME

	bool "RCU callback-batch backup time check"

	depends on RCU_EXPERT

kernel/rcu/tree.c

+7 −2
Original line number Diff line number Diff line
@@ -2753,6 +2753,9 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in) 
}



#ifdef CONFIG_RCU_LAZY

static bool enable_rcu_lazy __read_mostly = !IS_ENABLED(CONFIG_RCU_LAZY_DEFAULT_OFF);

module_param(enable_rcu_lazy, bool, 0444);



/**

 * call_rcu_hurry() - Queue RCU callback for invocation after grace period, and

 * flush all lazy callbacks (including the new one) to the main ->cblist while
@@ -2775,9 +2778,11 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in) 
 */

void call_rcu_hurry(struct rcu_head *head, rcu_callback_t func)

{

	return __call_rcu_common(head, func, false);

	__call_rcu_common(head, func, false);

}

EXPORT_SYMBOL_GPL(call_rcu_hurry);

#else

#define enable_rcu_lazy		false

#endif



/**
@@ -2826,7 +2831,7 @@ EXPORT_SYMBOL_GPL(call_rcu_hurry); 
 */

void call_rcu(struct rcu_head *head, rcu_callback_t func)

{

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

	__call_rcu_common(head, func, enable_rcu_lazy);

}

EXPORT_SYMBOL_GPL(call_rcu);