kernel_optimize_test/kernel/rcu
Paul E. McKenney 928164351e rcu: Prevent useless FQS scan after all CPUs have checked in
The force_qs_rnp() function checks for ->qsmask being all zero, that is,
all CPUs for the current rcu_node structure having already passed through
quiescent states.  But with RCU-preempt, this is not sufficient to report
quiescent states further up the tree, so there are further checks that
can initiate RCU priority boosting and also for races with CPU-hotplug
operations.  However, if neither of these further checks apply, the code
proceeds to carry out a useless scan of an all-zero ->qsmask.

This commit therefore adds code to release the current rcu_node
structure's lock and continue on to the next rcu_node structure, thereby
avoiding this useless scan.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2018-07-12 15:39:01 -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 License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
rcu_segcblist.c rcu: Simplify and inline cpu_needs_another_gp() 2018-05-15 10:30:59 -07:00
rcu_segcblist.h rcu: Simplify and inline cpu_needs_another_gp() 2018-05-15 10:30:59 -07:00
rcu.h rcutorture: Correctly handle grace-period sequence wrap 2018-07-12 15:38:55 -07:00
rcuperf.c rcutorture: Correctly handle grace-period sequence wrap 2018-07-12 15:38:55 -07:00
rcutorture.c rcutorture: Correctly handle grace-period sequence wrap 2018-07-12 15:38:55 -07:00
srcutiny.c srcu: Add cleanup_srcu_struct_quiesced() 2018-05-15 10:27:56 -07:00
srcutree.c rcutorture: Convert rcutorture_get_gp_data() to ->gp_seq 2018-07-12 14:27:57 -07:00
sync.c doc: Fix various RCU docbook comment-header problems 2017-10-19 22:26:11 -04:00
tiny.c srcu: Move rcu_scheduler_starting() from Tiny RCU to Tiny SRCU 2017-07-24 16:03:22 -07:00
tree_exp.h rcu: Make expedited GPs handle CPU 0 being offline 2018-07-12 12:36:06 -07:00
tree_plugin.h rcu: Fix typo and add additional debug 2018-07-12 15:39:00 -07:00
tree.c rcu: Prevent useless FQS scan after all CPUs have checked in 2018-07-12 15:39:01 -07:00
tree.h rcu: Remove ->gpnum and ->completed 2018-07-12 15:38:48 -07:00
update.c rcu: Move __rcu_read_lock() and __rcu_read_unlock() to tree_plugin.h 2018-05-15 10:27:41 -07:00