path: root/docs/report/introduction/methodology.rst

Performance Test Methodology
============================

Throughput
----------

Packet and bandwidth throughput are measured in accordance with
:rfc:`2544`, using FD.io CSIT Multiple Loss Ratio search (MLRsearch), an
optimized binary search algorithm, that measures SUT/DUT throughput at
different Packet Loss Ratio (PLR) values.

Following MLRsearch values are measured across a range of L2 frame sizes
and reported:

- **Non Drop Rate (NDR)**: packet and bandwidth throughput at PLR=0%.

  - **Aggregate packet rate**: NDR_LOWER <bi-directional packet rate>
    pps.
  - **Aggregate bandwidth rate**: NDR_LOWER <bi-directional bandwidth
    rate> Gbps.

- **Partial Drop Rate (PDR)**: packet and bandwidth throughput at
  PLR=0.5%.

  - **Aggregate packet rate**: PDR_LOWER <bi-directional packet rate>
    pps.
  - **Aggregate bandwidth rate**: PDR_LOWER <bi-directional bandwidth
    rate> Gbps.

NDR and PDR are measured for the following L2 frame sizes (untagged
Ethernet):

- IPv4 payload: 64B, IMIX_v4_1 (28x64B, 16x570B, 4x1518B), 1518B, 9000B.
- IPv6 payload: 78B, 1518B, 9000B.

All rates are reported from external Traffic Generator perspective.

Description of MLRsearch algorithm is provided in
:ref:`mlrsearch_algorithm`.

Maximum Receive Rate MRR
------------------------

MRR tests measure the packet forwarding rate under the maximum
load offered by traffic generator over a set trial duration,
regardless of packet loss. Maximum load for specified Ethernet frame
size is set to the bi-directional link rate.

Current parameters for MRR tests:

- Ethernet frame sizes: 64B (78B for IPv6), IMIX, 1518B, 9000B; all
  quoted sizes include frame CRC, but exclude per frame transmission
  overhead of 20B (preamble, inter frame gap).

- Maximum load offered: 10GE and 40GE link (sub-)rates depending on NIC
  tested, with the actual packet rate depending on frame size,
  transmission overhead and traffic generator NIC forwarding capacity.

  - For 10GE NICs the maximum packet rate load is 2* 14.88 Mpps for 64B,
    a 10GE bi-directional link rate.
  - For 25GE NICs the maximum packet rate load is 2* 18.75 Mpps for 64B,
    a 25GE bi-directional link sub-rate limited by TG 25GE NIC used,
    XXV710.
  - For 40GE NICs the maximum packet rate load is 2* 18.75 Mpps for 64B,
    a 40GE bi-directional link sub-rate limited by TG 40GE NIC used,
    XL710. Packet rate for other tested frame sizes is limited by PCIe
    Gen3 x8 bandwidth limitation of ~50Gbps.

- Trial duration: 10sec.

Similarly to NDR/PDR throughput tests, MRR test should be reporting bi-
directional link rate (or NIC rate, if lower) if tested VPP
configuration can handle the packet rate higher than bi-directional link
rate, e.g. large packet tests and/or multi-core tests.

MRR tests are used for continuous performance trending and for
comparison between releases. Daily trending job tests subset of frame
sizes, focusing on 64B (78B for IPv6) for all tests and IMIX for
selected tests (vhost, memif).

Packet Latency
--------------

TRex Traffic Generator (TG) is used for measuring latency of VPP DUTs.
Reported latency values are measured using following methodology:

- Latency tests are performed at 100% of discovered NDR and PDR rates
  for each throughput test and packet size (except IMIX).
- TG sends dedicated latency streams, one per direction, each at the
  rate of 9 kpps at the prescribed packet size; these are sent in
  addition to the main load streams.
- TG reports min/avg/max latency values per stream direction, hence two
  sets of latency values are reported per test case; future release of
  TRex is expected to report latency percentiles.
- Reported latency values are aggregate across two SUTs due to three
  node topology used for all performance tests; for per SUT latency,
  reported value should be divided by two.
- 1usec is the measurement accuracy advertised by TRex TG for the setup
  used in FD.io labs used by CSIT project.
- TRex setup introduces an always-on error of about 2*2usec per latency
  flow additonal Tx/Rx interface latency induced by TRex SW writing and
  reading packet timestamps on CPU cores without HW acceleration on NICs
  closer to the interface line.

Multi-Core Speedup
------------------

All performance tests are executed with single processor core and with
multiple cores scenarios.

Intel Hyper-Threading (HT)
~~~~~~~~~~~~~~~~~~~~~~~~~~

Intel Xeon processors used in FD.io CSIT can operate either in HT
Disabled mode (single logical core per each physical core) or in HT
Enabled mode (two logical cores per each physical core). HT setting is
applied in BIOS and requires server SUT reload for it to take effect,
making it impractical for continuous changes of HT mode of operation.

|csit-release| performance tests are executed with server SUTs' Intel
XEON processors configured with Intel Hyper-Threading Disabled for all
Xeon Haswell testbeds (3n-hsw) and with Intel Hyper-Threading Enabled
for all Xeon Skylake testbeds.

More information about physical testbeds is provided in
:ref:`tested_physical_topologies`.

Multi-core Tests
~~~~~~~~~~~~~~~~

|csit-release| multi-core tests are executed in the following VPP worker
thread and physical core configurations:

#. Intel Xeon Haswell testbeds (3n-hsw) with Intel HT disabled
   (1 logical CPU core per each physical core):

  #. 1t1c - 1 VPP worker thread on 1 physical core.
  #. 2t2c - 2 VPP worker threads on 2 physical cores.
  #. 4t4c - 4 VPP worker threads on 4 physical cores.

#. Intel Xeon Skylake testbeds (2n-skx, 3n-skx) with Intel HT enabled
   (2 logical CPU cores per each physical core):

  #. 2t1c - 2 VPP worker threads on 1 physical core.
  #. 4t2c - 4 VPP worker threads on 2 physical cores.
  #. 8t4c - 8 VPP worker threads on 4 physical cores.

VPP worker threads are the data plane threads running on isolated
logical cores. With Intel HT enabled VPP workers are placed as sibling
threads on each used physical core. VPP control threads (main, stats)
are running on a separate non-isolated core together with other Linux
processes.

In all CSIT tests care is taken to ensure that each VPP worker handles
the same amount of received packet load and does the same amount of
packet processing work. This is achieved by evenly distributing per
interface type (e.g. physical, virtual) receive queues over VPP workers
using default VPP round- robin mapping and by loading these queues with
the same amount of packet flows.

If number of VPP workers is higher than number of physical or virtual
interfaces, multiple receive queues are configured on each interface.
NIC Receive Side Scaling (RSS) for physical interfaces and multi-queue
for virtual interfaces are used for this purpose.

Section :ref:`throughput_speedup_multi_core` includes a set of graphs
illustrating packet throughout speedup when running VPP worker threads
on multiple cores. Note that in quite a few test cases running VPP
workers on 2 or 4 physical cores hits the I/O bandwidth or packets-per-
second limit of tested NIC.

VPP Startup Settings
--------------------

CSIT code manipulates a number of VPP settings in startup.conf for optimized
performance. List of common settings applied to all tests and test
dependent settings follows.

See `VPP startup.conf <https://git.fd.io/vpp/tree/src/vpp/conf/startup.conf?h=stable/1807>`_
for a complete set and description of listed settings.

Common Settings
~~~~~~~~~~~~~~~

List of vpp startup.conf settings applied to all tests:

#. heap-size <value> - set separately for ip4, ip6, stats, main
   depending on scale tested.
#. no-tx-checksum-offload - disables UDP / TCP TX checksum offload in DPDK.
   Typically needed for use faster vector PMDs (together with
   no-multi-seg).
#. socket-mem <value>,<value> - memory per numa. (Not required anymore
   due to VPP code changes, should be removed in CSIT rls1810.)

Per Test Settings
~~~~~~~~~~~~~~~~~

List of vpp startup.conf settings applied dynamically per test:

#. corelist-workers <list_of_cores> - list of logical cores to run VPP
   worker data plane threads. Depends on HyperThreading and core per
   test configuration.
#. num-rx-queues <value> - depends on a number of VPP threads and NIC
   interfaces.
#. num-rx-desc/num-tx-desc - number of rx/tx descriptors for specific
   NICs, incl. xl710, x710, xxv710.
#. num-mbufs <value> - increases number of buffers allocated, needed
   only in scenarios with large number of interfaces and worker threads.
   Value is per CPU socket. Default is 16384.
#. no-multi-seg - disables multi-segment buffers in DPDK, improves
   packet throughput, but disables Jumbo MTU support. Disabled for all
   tests apart from the ones that require Jumbo 9000B frame support.
#. UIO driver - depends on topology file definition.
#. QAT VFs - depends on NRThreads, each thread = 1QAT VFs.

KVM VMs vhost-user
------------------

FD.io CSIT performance lab is testing VPP vhost with KVM VMs using
following environment settings:

- Tests with varying Qemu virtio queue (a.k.a. vring) sizes: [vr256]
  default 256 descriptors, [vr1024] 1024 descriptors to optimize for
  packet throughput.
- Tests with varying Linux :abbr:`CFS (Completely Fair Scheduler)`
  settings: [cfs] default settings, [cfsrr1] CFS RoundRobin(1) policy
  applied to all data plane threads handling test packet path including
  all VPP worker threads and all Qemu testpmd poll-mode threads.
- Resulting test cases are all combinations with [vr256,vr1024] and
  [cfs,cfsrr1] settings.
- Adjusted Linux kernel :abbr:`CFS (Completely Fair Scheduler)`
  scheduler policy for data plane threads used in CSIT is documented in
  `CSIT Performance Environment Tuning wiki <https://wiki.fd.io/view/CSIT/csit-perf-env-tuning-ubuntu1604>`_.
- The purpose is to verify performance impact (MRR and NDR/PDR
  throughput) and same test measurements repeatability, by making VPP
  and VM data plane threads less susceptible to other Linux OS system
  tasks hijacking CPU cores running those data plane threads.

LXC/DRC Container Memif
-----------------------

|csit-release| includes tests taking advantage of VPP memif virtual
interface (shared memory interface) to interconnect VPP running in
Containers. VPP vswitch instance runs in bare-metal user-mode handling
NIC interfaces and connecting over memif (Slave side) to VPPs running in
:abbr:`Linux Container (LXC)` or in Docker Container (DRC) configured
with memif (Master side). LXCs and DRCs run in a priviliged mode with
VPP data plane worker threads pinned to dedicated physical CPU cores per
usual CSIT practice. All VPP instances run the same version of software.
This test topology is equivalent to existing tests with vhost-user and
VMs as described earlier in :ref:`tested_logical_topologies`.

In addition to above vswitch tests, a single memif interface test is
executed. It runs in a simple topology of two VPP container instances
connected over memif interface in order to verify standalone memif
interface performance.

More information about CSIT LXC and DRC setup and control is available
in :ref:`container_orchestration_in_csit`.

K8s Container Memif
-------------------

|csit-release| includes tests of VPP topologies running in K8s
orchestrated Pods/Containers and connected over memif virtual
interfaces. In order to provide simple topology coding flexibility and
extensibility container orchestration is done with `Kubernetes
<https://github.com/kubernetes>`_ using `Docker
<https://github.com/docker>`_ images for all container applications
including VPP. `Ligato <https://github.com/ligato>`_ is used for the
Pod/Container networking orchestration that is integrated with K8s,
including memif support.

In these tests VPP vswitch runs in a K8s Pod with Docker Container (DRC)
handling NIC interfaces and connecting over memif to more instances of
VPP running in Pods/DRCs. All DRCs run in a priviliged mode with VPP
data plane worker threads pinned to dedicated physical CPU cores per
usual CSIT practice. All VPP instances run the same version of software.
This test topology is equivalent to existing tests with vhost-user and
VMs as described earlier in :ref:`tested_physical_topologies`.

Further documentation is available in
:ref:`container_orchestration_in_csit`.

IPSec on Intel QAT
------------------

VPP IPSec performance tests are using DPDK cryptodev device driver in
combination with HW cryptodev devices - Intel QAT 8950 50G - present in
LF FD.io physical testbeds. DPDK cryptodev can be used for all IPSec
data plane functions supported by VPP.

Currently |csit-release| implements following IPSec test cases:

- AES-GCM, CBC-SHA1 ciphers, in combination with IPv4 routed-forwarding
  with Intel xl710 NIC.
- CBC-SHA1 ciphers, in combination with LISP-GPE overlay tunneling for
  IPv4-over-IPv4 with Intel xl710 NIC.

TRex Traffic Generator
----------------------

Usage
~~~~~

`TRex traffic generator <https://wiki.fd.io/view/TRex>`_ is used for all
CSIT performance tests. TRex stateless mode is used to measure NDR and
PDR throughputs using binary search (NDR and PDR discovery tests) and
for quick checks of DUT performance against the reference NDRs (NDR
check tests) for specific configuration.

TRex is installed and run on the TG compute node. The typical procedure
is:

- If the TRex is not already installed on TG, it is installed in the
  suite setup phase - see `TRex intallation`_.
- TRex configuration is set in its configuration file
  ::

  /etc/trex_cfg.yaml

- TRex is started in the background mode
  ::

  $ sh -c 'cd <t-rex-install-dir>/scripts/ && sudo nohup ./t-rex-64 -i -c 7 --iom 0 > /tmp/trex.log 2>&1 &' > /dev/null

- There are traffic streams dynamically prepared for each test, based on traffic
  profiles. The traffic is sent and the statistics obtained using
  :command:`trex_stl_lib.api.STLClient`.

Measuring Packet Loss
~~~~~~~~~~~~~~~~~~~~~

Following sequence is followed to measure packet loss:

- Create an instance of STLClient.
- Connect to the client.
- Add all streams.
- Clear statistics.
- Send the traffic for defined time.
- Get the statistics.

If there is a warm-up phase required, the traffic is sent also before
test and the statistics are ignored.

Measuring Latency
~~~~~~~~~~~~~~~~~

If measurement of latency is requested, two more packet streams are
created (one for each direction) with TRex flow_stats parameter set to
STLFlowLatencyStats. In that case, returned statistics will also include
min/avg/max latency values.

HTTP/TCP with WRK tool
----------------------

`WRK HTTP benchmarking tool <https://github.com/wg/wrk>`_ is used for
experimental TCP/IP and HTTP tests of VPP TCP/IP stack and built-in
static HTTP server. WRK has been chosen as it is capable of generating
significant TCP/IP and HTTP loads by scaling number of threads across
multi-core processors.

This in turn enables quite high scale benchmarking of the main TCP/IP
and HTTP service including HTTP TCP/IP Connections-Per-Second (CPS),
HTTP Requests-Per-Second and HTTP Bandwidth Throughput.

The initial tests are designed as follows:

- HTTP and TCP/IP Connections-Per-Second (CPS)

  - WRK configured to use 8 threads across 8 cores, 1 thread per core.
  - Maximum of 50 concurrent connections across all WRK threads.
  - Timeout for server responses set to 5 seconds.
  - Test duration is 30 seconds.
  - Expected HTTP test sequence:

    - Single HTTP GET Request sent per open connection.
    - Connection close after valid HTTP reply.
    - Resulting flow sequence - 8 packets: >Syn, <Syn-Ack, >Ack, >Req,
      <Rep, >Fin, <Fin, >Ack.

- HTTP Requests-Per-Second

  - WRK configured to use 8 threads across 8 cores, 1 thread per core.
  - Maximum of 50 concurrent connections across all WRK threads.
  - Timeout for server responses set to 5 seconds.
  - Test duration is 30 seconds.
  - Expected HTTP test sequence:

    - Multiple HTTP GET Requests sent in sequence per open connection.
    - Connection close after set test duration time.
    - Resulting flow sequence: >Syn, <Syn-Ack, >Ack, >Req[1], <Rep[1],
      .., >Req[n], <Rep[n], >Fin, <Fin, >Ack.