Paul E. McKenney 3a19b46a5c rcu: Check cond_resched_rcu_qs() state less often to reduce GP overhead ... Commit 4a81e8328d ("rcu: Reduce overhead of cond_resched() checks for RCU") moved quiescent-state generation out of cond_resched() and commit bde6c3aa99 ("rcu: Provide cond_resched_rcu_qs() to force quiescent states in long loops") introduced cond_resched_rcu_qs(), and commit 5cd37193ce ("rcu: Make cond_resched_rcu_qs() apply to normal RCU flavors") introduced the per-CPU rcu_qs_ctr variable, which is frequently polled by the RCU core state machine. This frequent polling can increase grace-period rate, which in turn increases grace-period overhead, which is visible in some benchmarks (for example, the "open1" benchmark in Anton Blanchard's "will it scale" suite). This commit therefore reduces the rate at which rcu_qs_ctr is polled by moving that polling into the force-quiescent-state (FQS) machinery, and by further polling it only after the grace period has been in effect for at least jiffies_till_sched_qs jiffies. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>		2017-01-23 11:44:18 -08:00
..
Makefile	rcutorture: Add RCU grace-period performance tests	2016-03-31 13:37:38 -07:00
rcu.h	rcu: Narrow early boot window of illegal synchronous grace periods	2017-01-14 21:23:48 -08:00
rcuperf.c	rcuperf: Consistently insert space between flag and message	2016-08-22 10:06:16 -07:00
rcutorture.c	torture: Trace long read-side delays	2016-11-14 10:46:30 -08:00
srcu.c	rcu: Add rcu_normal kernel parameter to suppress expediting	2015-12-04 12:26:53 -08:00
sync.c	locking, rcu, cgroup: Avoid synchronize_sched() in __cgroup_procs_write()	2016-08-18 15:36:59 +02:00
tiny_plugin.h	rcu: Narrow early boot window of illegal synchronous grace periods	2017-01-14 21:23:48 -08:00
tiny.c	rcu: Remove cond_resched() from Tiny synchronize_sched()	2017-01-14 21:22:20 -08:00
tree_exp.h	rcu: Abstract extended quiescent state determination	2017-01-23 11:44:18 -08:00
tree_plugin.h	rcu: Abstract extended quiescent state determination	2017-01-23 11:44:18 -08:00
tree_trace.c	rcu: Abstract extended quiescent state determination	2017-01-23 11:44:18 -08:00
tree.c	rcu: Check cond_resched_rcu_qs() state less often to reduce GP overhead	2017-01-23 11:44:18 -08:00
tree.h	rcu: Abstract extended quiescent state determination	2017-01-23 11:44:18 -08:00
update.c	rcu: Narrow early boot window of illegal synchronous grace periods	2017-01-14 21:23:48 -08:00