net: frag performance tuning cachelines for NUMA/SMP systems

This patchset is V2, with some trivial code fixes, which were noticed by DaveM. It is still a partly respin of my fragmentation optimization
patches: http://thread.gmane.org/gmane.linux.network/250914

This is not the complete patchset, from the gmane link above. In this patchset, I primarily focus on adjusting cacheline for better SMP/NUMA performance.

Once this patchset have been agreed upon, I will continue and respin the rest of my patches.

This time around, I have created a frag DoS generator, via the tool trafgen (http://netsniff-ng.org/). To create a stable DoS scenario (no longer relying on frame dropping due to disabled flow-control).

Two 10G interfaces are under-test, and uses Ethernet flow-control. A third interface is used for generating the DoS attack (this interface is also 10G, but it does not need to be, as 500Kpps DoS is enough).

Test types summary (netperf):
Test-20G64K == 2x10G with 65K fragments
Test-20G3F == 2x10G with 3x fragments (3*1472 bytes)
Test-20G64K+DoS == Same as 20G64K with frag DoS
Test-20G3F+DoS == Same as 20G3F with frag DoS

Patch list:
Patch-01 - net: cacheline adjust struct netns_frags for better frag performance Patch-02 - net: cacheline adjust struct inet_frags for better frag performance Patch-03 - net: cacheline adjust struct inet_frag_queue
Patch-04 - net: frag helper functions for mem limit tracking Patch-05 - net: use lib/percpu_counter API for fragmentation mem accounting Patch-06 - net: frag, move LRU list maintenance outside of rwlock

Performance table summary:

 Test-type:  Test-20G64K    Test-20G3F  20G64K+DoS   20G3F+DoS
 ----------  -----------    ----------  ----------   ---------
  net-next:  15114.5 Mbit/s   8954.21     2444.28     3918.01 Mbit/s
  Patch-01:  16075.8 Mbit/s   8976.18     2621.49     4072.79 Mbit/s
  Patch-02:  17806.9 Mbit/s   9280.32     2478.62     4274.59 Mbit/s
  Patch-03:  17317.4 Mbit/s   9308.62     2546.05     4336.59 Mbit/s
  Patch-04:  17635.9 Mbit/s   9256.16     2535.25     4327.63 Mbit/s
  Patch-05:  18027.0 Mbit/s   9918.99     2492.62     3621.68 Mbit/s
  Patch-06:  18486.7 Mbit/s  10723.20     3657.85     4560.64 Mbit/s

I cannot explain the under-DoS regression that patch-05/percpu_counter introduces. But patch-06/LRU-lock corrects the situation again.

Below is a testlab setup description, with links to the trafgen DoS packet config used.

---

Jesper Dangaard Brouer (6):
net: frag, move LRU list maintenance outside of rwlock
net: use lib/percpu_counter API for fragmentation mem accounting
net: frag helper functions for mem limit tracking
net: cacheline adjust struct inet_frag_queue
net: cacheline adjust struct inet_frags for better frag performance
net: cacheline adjust struct netns_frags for better frag performance

 include/net/inet_frag.h                 |   84 ++++++++++++++++++++++++++++---
 include/net/ipv6.h                      |    2 -
 net/ipv4/inet_fragment.c                |   39 ++++++++------
 net/ipv4/ip_fragment.c                  |   28 ++++------
 net/ipv6/netfilter/nf_conntrack_reasm.c |   11 ++--
 net/ipv6/reassembly.c                   |   10 +---
 6 files changed, 118 insertions(+), 56 deletions(-)

Testlab
=======

Server setup
------------
The machine acting as a server:
- 2x CPU (E5-2630)
- Thus a NUMA arch/machine
- 4x 10Gbit/s ports
- NICs 2x Intel Dual port 82599 based (driver ixgbe)

Setup:
- Interfaces uses Ethernet flow control
- Flush all iptables
- Remove all iptables related module.
- Kill irqbalance
- Pin each 10G NIC port to a *single* CPU each

Pinning can easily be done by command hacks::

for x in /proc/irq/*/eth8*/../smp_affinity_list ; do echo 1 > $x; done for x in /proc/irq/*/eth9*/../smp_affinity_list ; do echo 3 > $x; done for x in /proc/irq/*/eth31*/../smp_affinity_list; do echo 6 > $x; done for x in /proc/irq/*/eth32*/../smp_affinity_list; do echo 8 > $x; done

Notice NUMA setting: The CPU to NIC tying is carefully choosen according to the NUMA node setup. Thus, NICs connected to a PCI-e slot that is connected to a physical CPU socket are tied together.

Choosing only a single CPU per NIC (port) is just to ease provoking and debugging this performance issue. (In real setups, you can choose more CPU, just remember the NUMA node in the equation).

Tools
-----

Netperf is used, with option -T to ensure CPU binding. The netserver processes, are NAPI pinned::

numactl -m0 -c0 netserver
numactl -m1 -c 1 netserver -p 1337

I now have a frag DoS generator, created via the tool:
trafgen (see: http://netsniff-ng.org/)

Trafgen packet config file:
http://people.netfilter.org/hawk/frag_work/trafgen/frag_packet03_small_frag.txf

Notice, I'm using features of trafgen, recently developed by Daniel Borkmann, thus you need the latest git tree to use my trafgen packet config.

git://github.com/borkmann/netsniff-ng.git

Command line:
trafgen --dev eth51 --conf frag_packet03_small_frag.txf -V -k 100 --cpus 2

Tests types
-----------

Test(20G64K) UDP-64K 2x 10Gbit/s with no DoS traffic:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

export SIZE=$((65507)); export TIME=$((20)); export LOG=/tmp/netperf.log ;\
netperf -p 1337 -H 192.168.31.2 -T7,7 -t UDP_STREAM -l $TIME -- -m $SIZE >> ${LOG}.31 &\
netperf -H 192.168.81.2 -T2,2 -t UDP_STREAM -l $TIME -- -m $SIZE >> ${LOG}.81 && \
wait $! && tail -n3 ${LOG}.* && \
tail -n3 ${LOG}.{31,81} | awk 'BEGIN{sum=0;} /212992 / {sum+=$4; print " +"$4} /==/ {print " file:"$2} END{print "sum:"sum" Mbit/s"}'

Test(20G3F) UDP-3xfrags 2x 10Gbit/s with no DoS traffic:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

export SIZE=$((3*1472)); export TIME=$((20)); export LOG=/tmp/netperf.log ;\
netperf -p 1337 -H 192.168.31.2 -T7,7 -t UDP_STREAM -l $TIME -- -m $SIZE >> ${LOG}.31 &\
netperf -H 192.168.81.2 -T2,2 -t UDP_STREAM -l $TIME -- -m $SIZE >> ${LOG}.81 && \
wait $! && tail -n3 ${LOG}.* && \
tail -n3 ${LOG}.{31,81} | awk 'BEGIN{sum=0;} /212992 / {sum+=$4; print " +"$4} /==/ {print " file:"$2} END{print "sum:"sum" Mbit/s"}'

Awk script for summming results:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tail -n3 ${LOG}.{31,81} | awk 'BEGIN{sum=0;} /212992 / {sum+=$4; print " +"$4} /==/ {print " file:"$2} END{print "sum:"sum" Mbit/s"}'

--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Sr. Network Kernel Developer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer