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@xxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Josh Cartwright <joshc@xxxxxx>
---
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-rt-users" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
