linux/kernel/rcu
Paul E. McKenney f79c3ad618 sched,rcu: Make cond_resched() provide RCU quiescent state
There is some confusion as to which of cond_resched() or
cond_resched_rcu_qs() should be added to long in-kernel loops.
This commit therefore eliminates the decision by adding RCU quiescent
states to cond_resched().  This commit also simplifies the code that
used to interact with cond_resched_rcu_qs(), and that now interacts with
cond_resched(), to reduce its overhead.  This reduction is necessary to
allow the heavier-weight cond_resched_rcu_qs() mechanism to be invoked
everywhere that cond_resched() is invoked.

Part of that reduction in overhead converts the jiffies_till_sched_qs
kernel parameter to read-only at runtime, thus eliminating the need for
bounds checking.

Reported-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
[ paulmck: Keep PREEMPT=n cond_resched a no-op, per Peter Zijlstra. ]
2017-10-09 14:25:17 -07:00
..
Kconfig rcu: Drive TASKS_RCU directly off of PREEMPT 2017-08-17 07:26:04 -07:00
Kconfig.debug rcu: Move RCU debug Kconfig options to kernel/rcu 2017-06-08 18:52:44 -07:00
Makefile rcu: Remove debugfs tracing 2017-06-08 18:52:43 -07:00
rcu.h rcu: Move rcu.h to new trivial-function style 2017-08-17 07:26:06 -07:00
rcu_segcblist.c rcu: Remove unused RCU list functions 2017-07-25 13:04:49 -07:00
rcu_segcblist.h rcu: Remove unused RCU list functions 2017-07-25 13:04:49 -07:00
rcuperf.c rcu: Remove CONFIG_TASKS_RCU ifdef from rcuperf.c 2017-07-24 16:04:09 -07:00
rcutorture.c Merge branches 'doc.2017.08.17a', 'fixes.2017.08.17a', 'hotplug.2017.07.25b', 'misc.2017.08.17a', 'spin_unlock_wait_no.2017.08.17a', 'srcu.2017.07.27c' and 'torture.2017.07.24c' into HEAD 2017-08-17 08:10:04 -07:00
srcutiny.c srcu: Move rcu_scheduler_starting() from Tiny RCU to Tiny SRCU 2017-07-24 16:03:22 -07:00
srcutree.c Merge branches 'doc.2017.08.17a', 'fixes.2017.08.17a', 'hotplug.2017.07.25b', 'misc.2017.08.17a', 'spin_unlock_wait_no.2017.08.17a', 'srcu.2017.07.27c' and 'torture.2017.07.24c' into HEAD 2017-08-17 08:10:04 -07:00
sync.c locking, rcu, cgroup: Avoid synchronize_sched() in __cgroup_procs_write() 2016-08-18 15:36:59 +02:00
tiny.c srcu: Move rcu_scheduler_starting() from Tiny RCU to Tiny SRCU 2017-07-24 16:03:22 -07:00
tree.c sched,rcu: Make cond_resched() provide RCU quiescent state 2017-10-09 14:25:17 -07:00
tree.h Merge branches 'doc.2017.08.17a', 'fixes.2017.08.17a', 'hotplug.2017.07.25b', 'misc.2017.08.17a', 'spin_unlock_wait_no.2017.08.17a', 'srcu.2017.07.27c' and 'torture.2017.07.24c' into HEAD 2017-08-17 08:10:04 -07:00
tree_exp.h rcu: Make expedited GPs correctly handle hardware CPU insertion 2017-07-25 13:04:45 -07:00
tree_plugin.h treewide: make "nr_cpu_ids" unsigned 2017-09-08 18:26:48 -07:00
update.c rcu: Create reasonable API for do_exit() TASKS_RCU processing 2017-08-17 07:26:05 -07:00