ofproto-dpif-xlate: Wildcard skb_priority if QoS is disabled

This optimization should give a small performance benefit to the userspace
datapath.

Signed-off-by: Daniele Di Proietto <ddiproietto@vmware.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>
dpif-netdev: Introduce netdev_flow_key_* functions

netdev_flow_key is a miniflow with the following constraints:

1) It is used only inside dpif-netdev.c.
2) It always has inline values.
3) It contains only miniflows created by miniflow_extract().

Therefore, by using these new functions instead of the miniflow_*
ones, we get the following (performance related) benefits:

- Because of (1) the functions can be inlined.
- Because of (2) and (3) the netdev_flow_key can be treated as POD.
  Specifically, because of (3), we can do comparisons with memcmp,
  since if the map is different the miniflow must be different.

Signed-off-by: Daniele Di Proietto <ddiproietto@vmware.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>
dpif-netdev: Store miniflow length in exact match cache

This optimization is done to avoid calling count_1bits(), which, if
the popcnt istruction is not available might is slow. popcnt may not
be available because:

- We are running on old hardware
- (more likely) We're using a generic build (i.e. packaged OVS from a
  distro), not tuned for the specific CPU

Signed-off-by: Daniele Di Proietto <ddiproietto@vmware.com>
Acked-by: Jarno Rajahalme <jrajahalme@nicira.com>
ofproto: Warn about excessive rule counts in OpenFlow tables.

Frequently we've run into controller bugs which result in hundreds of
thousands, or even millions of rules being installed in an OpenFlow
table.  This isn't something trouble-shooters naturally think of to
check for, so it's nice to have a low rate warning message to hint at
the potential problem.

Signed-off-by: Ethan Jackson <ethan@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>