This reverts commit be3fc413da9eb17cce0991f214ab019d16c88c41. While the use of synchronize_rcu_expedited() might make synchronize_net() "faster", it does so at significant cost on RT systems, as expediting a grace period forcibly preempts any high-priority RT tasks (via the stop_machine() mechanism).
Without be3fc413da9e reverted, we can observe a latency spike up to 30us with cyclictest by rapidly unplugging/reestablishing an ethernet link. Cc: Eric Dumazet <[email protected]> Cc: Paul E. McKenney <[email protected]> Cc: David S. Miller <[email protected]> Signed-off-by: Josh Cartwright <[email protected]> --- net/core/dev.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/net/core/dev.c b/net/core/dev.c index f8c23de..869ef62 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6969,10 +6969,7 @@ EXPORT_SYMBOL(free_netdev); void synchronize_net(void) { might_sleep(); - if (rtnl_is_locked()) - synchronize_rcu_expedited(); - else - synchronize_rcu(); + synchronize_rcu(); } EXPORT_SYMBOL(synchronize_net); -- 2.5.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
