Messages in this thread Patch in this message | | | From | Josh Cartwright <> | Subject | [PATCH -rt] Revert "net: use synchronize_rcu_expedited()" | Date | Mon, 26 Oct 2015 14:14:55 -0500 |
| |
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 <eric.dumazet@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Josh Cartwright <joshc@ni.com> --- 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
| |