We've been seeing lots of cache line contention (but not lock contention!)
in our workloads between the various TX and RX threads going on.
The write lock is only grabbed when configuration changes are made - which
are infrequent.
With this patch, the contention and cycles spent waiting for updates
disappear.
Sponsored by: Netflix, Inc.
sysctl tree.
* Create a net.link.lagg.X.lacp node
* Add a debug node under that for tx_test and rx_test
* Add lacp_strict_mode, defaulting to 1
tx_test and rx_test are still a bitmap of unit numbers for now.
At some point it would be nice to create child nodes of the lagg bundle
for each sub-interface, and then populate those with various knobs
and statistics.
Sponsored by: Netflix
additions.
* Add some new tracing events to aid in debugging.
* Add in a debugging mode to drop transmit and received frames, specifically
to test whether seeing or hearing heartbeats correctly cause LACP to
drop the port.
* Add in (and make default) a strict LACP mode, which requires the
heartbeat on a port to be heard before it's used. Sometimes vendor ports
will hang but the link layer stays up, resulting in hung traffic.
* Add logging the number of link status flaps, again to aid in debugging
badly behaving switch ports.
* Calculate the lagg interface port speed as the multiple of the
configured ports, rather than the largest.
Obtained from: Netflix
MFC after: 2 weeks
The lagg(4) is often used to bond high speed links, so basic per-packet +=
on statistics cause cache misses and statistics loss.
Perfect solution would be to convert ifnet(9) to counters(9), but this
requires much more work, and unfortunately ABI change, so temporarily
patch lagg(4) manually.
We store counters in the softc, and once per second push their values
to legacy ifnet counters.
Sponsored by: Nginx, Inc.
the traffic flow, this may not be the case giving poor traffic distribution.
Add a sysctl which allows us to fall back to our own flow hash code.
PR: kern/164901
Submitted by: Eugene Grosbein
MFC after: 1 week
1. The locking was changed to shared but roundrobin mode still updated a
pointer in the softc with the next tx interface to use. This will panic
under high load. Change this to an atomically incremented sequence number in
order to choose the tx port in round robin.
2. IFQ_HANDOFF will free the mbuf if the queue is full, this will then be freed
again by lagg_start() and panic. Reorganised the error handling and freeing
to fix this.
MFC after: 3 days
ports to the lagg interface.
- Use the MTU from the first interface as the lagg MTU, all extra interfaces
must be the same.
This fixes using a lagg interface for a vlan or enabling jumbo frames, etc.
Approved by: re (kensmith)
MFC After: 3 days
The name trunk is misused as the networking term trunk means carrying multiple
VLANs over a single connection. The IEEE standard for link aggregation (802.3
section 3) does not talk about 'trunk' at all while it is used throughout IEEE
802.1Q in describing vlans.
The lagg(4) driver provides link aggregation, failover and fault tolerance.
Discussed on: current@
