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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-03-16 11:53:52 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-05-27 12:58:01 -0700 |
| commit | cd73ca21cd2bb3711b8d80ba74c90d37ef15fe4d (patch) | |
| tree | af8915695057dad40b62a592a99d608de815d9d3 | |
| parent | 3382adbc1bb8c80ea512243acf6059564287620b (diff) | |
| download | op-kernel-dev-cd73ca21cd2bb3711b8d80ba74c90d37ef15fe4d.zip op-kernel-dev-cd73ca21cd2bb3711b8d80ba74c90d37ef15fe4d.tar.gz | |
rcu: Force wakeup of rcu_gp_kthread at grace-period end
The rcu_gp_kthread_wake() refuses to do a wakeup unless at least
one of the ->gp_flags bits are set, which normally will not be the
case when the last quiescent state is reported. This results in
up to a 3-jiffy delay given default Kconfig settings. This commit
therefore has rcu_report_qs_rsp() set RCU_GP_FLAG_FQS before invoking
rcu_gp_kthread_wake() in order to force a more immediate wakeup at
grace-period end, thus reducing grace-period latencies.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| -rw-r--r-- | kernel/rcu/tree.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 213f644..7d369b8 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2139,6 +2139,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags) __releases(rcu_get_root(rsp)->lock) { WARN_ON_ONCE(!rcu_gp_in_progress(rsp)); + WRITE_ONCE(rsp->gp_flags, READ_ONCE(rsp->gp_flags) | RCU_GP_FLAG_FQS); raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags); rcu_gp_kthread_wake(rsp); } |
