From 026ad2835ce6202069e7aa0b11f5f1be4de34550 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 3 Apr 2013 22:14:11 -0700 Subject: rcu: Drive quiescent-state-forcing delay from HZ Systems with HZ=100 can have slow bootup times due to the default three-jiffy delays between quiescent-state forcing attempts. This commit therefore auto-tunes the RCU_JIFFIES_TILL_FORCE_QS value based on the value of HZ. However, this would break very large systems that require more time between quiescent-state forcing attempts. This commit therefore also ups the default delay by one jiffy for each 256 CPUs that might be on the system (based off of nr_cpu_ids at runtime, -not- NR_CPUS at build time). Updated to collapse #ifdefs for RCU_JIFFIES_TILL_FORCE_QS into a step-function definition as suggested by Josh Triplett. Reported-by: Paul Mackerras Signed-off-by: Paul E. McKenney --- kernel/rcutree.h | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) (limited to 'kernel/rcutree.h') diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 4df503470e42..4a39d364493c 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -343,12 +343,17 @@ struct rcu_data { #define RCU_FORCE_QS 3 /* Need to force quiescent state. */ #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK -#define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */ +#define RCU_JIFFIES_TILL_FORCE_QS (1 + (HZ > 250) + (HZ > 500)) + /* For jiffies_till_first_fqs and */ + /* and jiffies_till_next_fqs. */ -#define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time */ - /* to take at least one */ - /* scheduling clock irq */ - /* before ratting on them. */ +#define RCU_JIFFIES_FQS_DIV 256 /* Very large systems need more */ + /* delay between bouts of */ + /* quiescent-state forcing. */ + +#define RCU_STALL_RAT_DELAY 2 /* Allow other CPUs time to take */ + /* at least one scheduling clock */ + /* irq before ratting on them. */ #define rcu_wait(cond) \ do { \ -- cgit v1.2.3 From 49fb4c6290c70c418a5c25eee996d6b55ea132d6 Mon Sep 17 00:00:00 2001 From: Paul Gortmaker Date: Wed, 19 Jun 2013 14:52:21 -0400 Subject: rcu: delete __cpuinit usage from all rcu files The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the drivers/rcu uses of the __cpuinit macros from all C files. [1] https://lkml.org/lkml/2013/5/20/589 Cc: "Paul E. McKenney" Cc: Josh Triplett Cc: Dipankar Sarma Reviewed-by: Josh Triplett Signed-off-by: Paul Gortmaker --- kernel/rcutree.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/rcutree.h') diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 4a39d364493c..b3832581043c 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -521,10 +521,10 @@ static void invoke_rcu_callbacks_kthread(void); static bool rcu_is_callbacks_kthread(void); #ifdef CONFIG_RCU_BOOST static void rcu_preempt_do_callbacks(void); -static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, +static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp, struct rcu_node *rnp); #endif /* #ifdef CONFIG_RCU_BOOST */ -static void __cpuinit rcu_prepare_kthreads(int cpu); +static void rcu_prepare_kthreads(int cpu); static void rcu_cleanup_after_idle(int cpu); static void rcu_prepare_for_idle(int cpu); static void rcu_idle_count_callbacks_posted(void); -- cgit v1.2.3