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linux-next/kernel/rcu
Paul E. McKenney 22607d66bb srcu: Specify auto-expedite holdoff time
On small systems, in the absence of readers, expedited SRCU grace
periods can complete in less than a microsecond.  This means that an
eight-CPU system can have all CPUs doing synchronize_srcu() in a tight
loop and almost always expedite.  This might actually be desirable in
some situations, but in general it is a good way to needlessly burn
CPU cycles.  And in those situations where it is desirable, your friend
is the function synchronize_srcu_expedited().

For other situations, this commit adds a kernel parameter that specifies
a holdoff between completing the last SRCU grace period and auto-expediting
the next.  If the next grace period starts before the holdoff expires,
auto-expediting is disabled.  The holdoff is 50 microseconds by default,
and can be tuned to the desired number of nanoseconds.  A value of zero
disables auto-expediting.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Mike Galbraith <efault@gmx.de>
2017-04-26 16:32:17 -07:00
..
Makefile srcu: Introduce CLASSIC_SRCU Kconfig option 2017-04-18 11:38:23 -07:00
rcu.h srcu: Merge ->srcu_state into ->srcu_gp_seq 2017-04-18 11:38:22 -07:00
rcuperf.c sched/headers: Prepare for new header dependencies before moving code to <uapi/linux/sched/types.h> 2017-03-02 08:42:27 +01:00
rcutorture.c srcu: Make rcutorture writer stalls print SRCU GP state 2017-04-26 11:23:28 -07:00
srcu.c srcu: Introduce CLASSIC_SRCU Kconfig option 2017-04-18 11:38:23 -07:00
srcutiny.c srcu: Create a tiny SRCU 2017-04-18 11:38:22 -07:00
srcutree.c srcu: Specify auto-expedite holdoff time 2017-04-26 16:32:17 -07:00
sync.c locking, rcu, cgroup: Avoid synchronize_sched() in __cgroup_procs_write() 2016-08-18 15:36:59 +02:00
tiny_plugin.h srcu: Allow SRCU to access rcu_scheduler_active 2017-04-18 11:38:18 -07:00
tiny.c rcu: Semicolon inside RCU_TRACE() for Tiny RCU 2017-04-18 11:38:17 -07:00
tree_exp.h srcu: Improve rcu_seq grace-period-counter abstraction 2017-04-18 11:38:21 -07:00
tree_plugin.h Merge branches 'doc.2017.04.12a', 'fixes.2017.04.19a' and 'srcu.2017.04.21a' into HEAD 2017-04-21 06:00:13 -07:00
tree_trace.c srcu: Move rcu_init_levelspread() to rcu_tree_node.h 2017-04-18 11:38:20 -07:00
tree.c srcu: Make rcutorture writer stalls print SRCU GP state 2017-04-26 11:23:28 -07:00
tree.h srcu: Parallelize callback handling 2017-04-21 05:59:26 -07:00
update.c rcu: Make non-preemptive schedule be Tasks RCU quiescent state 2017-04-21 05:59:27 -07:00