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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-04-07 13:34:07 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2014-04-29 08:45:24 -0700 |
| commit | becb41bfe0544f1f7f494f48d6f68cbdb2e1ed0e (patch) | |
| tree | c71041b70966e689ccc7e667ce94e57f7469f047 /kernel/rcu | |
| parent | 5057f55e543b7859cfd26bc281291795eac93f8a (diff) | |
| download | linux-becb41bfe0544f1f7f494f48d6f68cbdb2e1ed0e.tar.gz | |
rcu: Make large and small sysidle systems use same state machine
Currently, small systems move back into RCU_SYSIDLE_NOT from RCU_SYSIDLE_SHORT and large systems do not. This works because moving aggressively to RCU_SYSIDLE_NOT affects only performance, not correctness, and on small systems, the performance impact should be negligible. That said, this difference does make RCU a bit more complex, and RCU does not seem to be suffering from any lack of complexity. This commit therefore adjusts small-system operation to match that of large systems, so that the state never moves back to RCU_SYSIDLE_NOT from RCU_SYSIDLE_SHORT. Reported-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree_plugin.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 045c6d04ed3f..f7593c2536b0 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -2659,7 +2659,8 @@ static void rcu_sysidle(unsigned long j) static void rcu_sysidle_cancel(void) { smp_mb(); - ACCESS_ONCE(full_sysidle_state) = RCU_SYSIDLE_NOT; + if (full_sysidle_state > RCU_SYSIDLE_SHORT) + ACCESS_ONCE(full_sysidle_state) = RCU_SYSIDLE_NOT; } /* |