From: "Paul E. McKenney" <[email protected]> This patch has been added to the 3.12 stable tree. If you have any objections, please let us know.
=============== commit c337f8f58ed7cf150651d232af8222421a71463d upstream. 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 <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> Tested-by: Tibor Billes <[email protected]> Reviewed-by: Josh Triplett <[email protected]> Signed-off-by: Jiri Slaby <[email protected]> --- kernel/rcutree_plugin.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index fd71cef0d789..d9cd0c2e34cb 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1739,6 +1739,8 @@ 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; } -- 1.9.0 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
