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Feature #4821

PPPoE WANs do not take full advantage of NIC driver queues for receiving traffic

Added by Jim Pingle over 1 year ago. Updated 13 days ago.

Status:
New
Priority:
Low
Assignee:
Category:
Interfaces
Target version:
Start date:
07/08/2015
Due date:
% Done:

0%


Description

On PPPoE WANs packets are only received on one NIC driver queue (queue0) while packets are transmitted from all queues (queue0 and queue1). This has been observed on multiple systems with PPPoE-based WANs and igb(4) NICs, though it may also affect L2TP and PPTP type WANs since they all use mpd.

On my WAN (igb1 with PPPoE on top):

dev.igb.1.queue0.tx_packets: 2535085
dev.igb.1.queue0.rx_packets: 5365670
dev.igb.1.queue1.tx_packets: 2711996
dev.igb.1.queue1.rx_packets: 0

Other non-PPPoE interfaces on the same unit, including additional WANs, show activity in all driver queues.

On another, different, firewall with igb(4) NICs and PPPoE, the same condition is present:

dev.igb.0.queue0.tx_packets: 8504662
dev.igb.0.queue0.rx_packets: 29342831
dev.igb.0.queue1.tx_packets: 3543617
dev.igb.0.queue1.rx_packets: 0

On lower speed WANs there are no negative effects, but on higher-speed PPPoE WANs such as gigabit links it can cause some disparity where traffic is transmitted at the expected rate but not received at the expected rate.

How to check (on systems with igb NICs):

sysctl -a | grep '\.igb\..*x_pack'

Look for the PPPoE WAN physical interface and check if has activity in the tx queue1 and rx queue1, or only the tx queue1 (or higher queues)

Currently only tested on pfSense 2.2.3-RELEASE amd64 images, needs more feedback/testing to confirm if it happens on additional versions/architectures.

History

#1 Updated by Steve Wheeler over 1 year ago

Seems likely to be this:
"Unfortunately, RSS is usually capable of hashing IPv4 and IPv4 traffic (L3+L4). All other traffic like PPPoE or MPLS or .. is usually received by queue 0."
https://wiki.freebsd.org/NetworkPerformanceTuning

There is a patch suggested there.

#2 Updated by Jim Thompson over 1 year ago

  • Tracker changed from Bug to Feature

#3 Updated by Jim Thompson over 1 year ago

  • Assignee set to Jim Thompson
  • Priority changed from Normal to Low
  • Target version changed from 2.3 to Future

Fixing this likely requires an in-kernel RSS (Toeplitz) implementation. Such a thing is coming for FreeBSD (Adrian is working on it for the upper layers of the stack), but it's going to be a while before it's ready to interface to netisr.

Priority dropped to "low". Will review when we're based on 11.

#4 Updated by Julien REVERT 9 months ago

Any news on this task? I'm deploying fiber internet on many pfsense APU2C4 and bandwith from wan is limited to 350 Mbits as soon as PPPoE is used (1 or the 4 cpu is 100% by PPPoE process). Otherwise (DHCP), fiber is at the top 950Mbits.

#5 Updated by Travis Erdmann 5 months ago

Now that FreeBSD 11 is out and PPPoE Gig internet is becoming more available, can we take another look at this?

#6 Updated by Sebastian Foss 5 months ago

Travis Erdmann wrote:

Now that FreeBSD 11 is out and PPPoE Gig internet is becoming more available, can we take another look at this?

Also happens on latests 2.4 Dev builds, but FreeBSD 11 includes the correct RSS awareness in the igb driver now.

#7 Updated by Jim Pingle 2 months ago

  • Target version changed from Future to 2.4.0

It still happens on 2.4, actually it's a little worse since it doesn't appear to transmit on the additional queues like it did previously:

dev.igb.1.queue1.rx_packets: 0
dev.igb.1.queue1.tx_packets: 0
dev.igb.1.queue0.rx_packets: 1978785
dev.igb.1.queue0.tx_packets: 1959503

Earlier note on the ticket said to review once we're on FreeBSD 11, so I'll set the target to 2.4 but it may need to be pushed again depending on what we find.

#8 Updated by Chris Allen 2 months ago

I would like to add that I am also experiencing this issue. I would love to see this fixed in pfSense 2.4 if possible. Jim Thompson do you have any idea what might be involved to fix this now that the FreeBSD 11 driver for igb has RSS awareness?

#9 Updated by Vladimir Putin about 2 months ago

According to this
https://lists.freebsd.org/pipermail/freebsd-net/2013-May/035564.html
Script that can solve CPU 1-core overload problem, but not default queue problem.


#!/bin/sh

# PROVIDE: cpuset-igb
# REQUIRE: FILESYSTEMS
# BEFORE:  netif
# KEYWORD: nojail

case "$1" in
*start)
  echo "Binding igb(4) IRQs to CPUs" 
  cpus=`sysctl -n kern.smp.cpus`
  vmstat -ai | sed -E '/^irq.*que/!d; s/^irq([0-9]+): igb([0-9]+):que ([0-9]+).*/\1 \2 \3/' |\
  while read irq igb que
  do
    cpuset -l $(( ($igb+$que) % $cpus )) -x $irq
  done
  ;;
esac

#10 Updated by Chris Allen 15 days ago

Hi Jim, just wondering if this is still something that might make it into pfSense 2.4.0? I would love to use the maximum speed of my Gigabit PPPoE Fibre connection on my APU2C4 :)

#11 Updated by Jim Thompson 13 days ago

Unlikely

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