Messages in this thread Patch in this message | | | From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 3/6] rcu: Throttle invoke_rcu_core() invocations due to non-lazy callbacks | Date | Tue, 24 Sep 2013 18:50:13 -0700 |
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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
If a non-lazy callback arrives on a CPU that has previously gone idle with no non-lazy callbacks, invoke_rcu_core() forces the RCU core to run. However, it does not update the conditions, which could result in several closely spaced invocations of the RCU core, which in turn could result in an excessively high context-switch rate and resulting high overhead.
This commit therefore updates the ->all_lazy and ->nonlazy_posted_snap fields to prevent closely spaced invocations.
Reported-by: Tibor Billes <tbilles@gmx.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: Tibor Billes <tbilles@gmx.com> --- kernel/rcutree_plugin.h | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index d81e385..2c15d7c 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1745,6 +1745,8 @@ static void rcu_prepare_for_idle(int cpu) */ if (rdtp->all_lazy && rdtp->nonlazy_posted != rdtp->nonlazy_posted_snap) { + rdtp->all_lazy = false; + rdtp->nonlazy_posted_snap = rdtp->nonlazy_posted; invoke_rcu_core(); return; } -- 1.8.1.5
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