Performance Testing

Performance subtests

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Environment setup

Autotest already supports prepare environment for performance testing, guest/host need to be reboot for some configuration. setup script

Autotest supports to numa pining. Assign “numanode=-1” in tests.cfg, then vcpu threads/vhost_net threads/VM memory will be pined to last numa node. If you want to pin other processes to numa node, you can use numctl and taskset.

memory:
$ numactl -m $n $cmdline
cpu:
$ taskset $node_mask $thread_id

The following content is manual guide.

1.First level pinning would be to use numa pinning when starting the guest.
e.g.  $ numactl -c 1 -m 1 qemu-kvm  -smp 2 -m 4G <> (pinning guest memory and cpus to numa-node 1)

2.For a single instance test, it would suggest trying a one to one mapping of vcpu to pyhsical core.
e.g.
get guest vcpu threads id
$ taskset -p 40 $vcpus1  #(pinning vcpu1 thread to pyshical cpu #6 )
$ taskset -p 80 $vcpus2  #(pinning vcpu2 thread to physical cpu #7 )

3.To pin vhost on host. get vhost PID and then use taskset to pin it on the same soket.
e.g
$ taskset -p 20 $vhost #(pinning vcpu2 thread to physical cpu #5 )

4.In guest,pin the IRQ to one core and the netperf to another.
1) make sure irqbalance is off - `$ service irqbalance stop`
2) find the interrupts - `$ cat /proc/interrupts`
3) find the affinity mask for the interrupt(s) - `$ cat /proc/irq/<irq#>/smp_affinity`
4) change the value to match the proper core.make sure the vlaue is cpu mask.
e.g. pin the IRQ to first core.
   $ echo 01>/proc/irq/$virti0-input/smp_affinity
   $ echo 01>/proc/irq/$virti0-output/smp_affinity
5)pin the netserver to another core.
e.g.
$ taskset -p 02 netserver

5.For host to guest scenario. to get maximum performance. make sure to run netperf on different cores on the same numa node as the guest.
e.g.
$ numactl -m 1 netperf -T 4 (pinning netperf to physical cpu #4)

Execute testing

  • Submit jobs in Autotest server, only execute netperf.guset_exhost for three times.

tests.cfg:

only netperf.guest_exhost
variants:
    - repeat1:
    - repeat2:
    - repeat3:
# vbr0 has a static ip: 192.168.100.16
bridge=vbr0
# virbr0 is created by libvirtd, guest nic2 get ip by dhcp
bridge_nic2 = virbr0
# guest nic1 static ip
ip_nic1 = 192.168.100.21
# external host static ip:
client = 192.168.100.15

Result files:

$ cd /usr/local/autotest/results/8-debug_user/192.168.122.1/
$ find .|grep RHS
kvm.repeat1.r61.virtio_blk.smp2.virtio_net.RHEL.6.1.x86_64.netperf.exhost_guest/results/netperf-result.RHS
kvm.repeat2.r61.virtio_blk.smp2.virtio_net.RHEL.6.1.x86_64.netperf.exhost_guest/results/netperf-result.RHS
kvm.repeat3.r61.virtio_blk.smp2.virtio_net.RHEL.6.1.x86_64.netperf.exhost_guest/results/netperf-result.RHS
  • Submit same job in another env (different packages) with same configuration

Result files:

$ cd /usr/local/autotest/results/9-debug_user/192.168.122.1/
$ find .|grep RHS
kvm.repeat1.r61.virtio_blk.smp2.virtio_net.RHEL.6.1.x86_64.netperf.exhost_guest/results/netperf-result.RHS
kvm.repeat2.r61.virtio_blk.smp2.virtio_net.RHEL.6.1.x86_64.netperf.exhost_guest/results/netperf-result.RHS
kvm.repeat3.r61.virtio_blk.smp2.virtio_net.RHEL.6.1.x86_64.netperf.exhost_guest/results/netperf-result.RHS

Analysis result

Config file: perf.conf

[ntttcp]
result_file_pattern = .*.RHS
ignore_col = 1
avg_update =

[netperf]
result_file_pattern = .*.RHS
ignore_col = 2
avg_update = 4,2,3|14,5,12|15,6,13

[iozone]
result_file_pattern =

Execute regression.py to compare two results:

login autotest server
$ cd /usr/local/autotest/client/tools
$ python regression.py netperf /usr/local/autotest/results/8-debug_user/192.168.122.1/ /usr/local/autotest/results/9-debug_user/192.168.122.1/

T-test:

Unpaired T-test is used to compare two samples, user can check p-value to know if regression bug exists. If the difference of two samples is considered to be not statistically significant(p <= 0.05), it will add a ‘+’ or ‘-‘ before p-value. (‘+’: avg_sample1 < avg_sample2, ‘-‘: avg_sample1 > avg_sample2)

  • - only over 95% confidence results will be added “+/-” in “Significance” part.
  • + for cpu-usage means regression, “+” for throughput means improvement.”

Regression results

  • Every Avg line represents the average value based on $n repetitions of the same test, and the following SD line represents the Standard Deviation between the $n repetitions.
  • The Standard deviation is displayed as a percentage of the average.
  • The significance of the differences between the two averages is calculated using unpaired T-test that takes into account the SD of the averages.
  • The paired t-test is computed for the averages of same category.
  • only over 95% confidence results will be added “+/-” in “Significance” part. “+” for cpu-usage means regression, “+” for throughput means improvement.

Highlight HTML result

  • green/red –> good/bad
  • Significance is larger than 0.95 –> green
  • dark green/red –> important (eg: cpu)
  • light green/red –> other
  • test time
  • version (only when diff)
  • other: repeat time, title
  • user light green/red to highlight small (< %5) DIFF
  • highlight Significance with same color in one raw
  • add doc link to result file, and describe color in doc

netperf.avg.html - Raw data that the averages are based on.