EVE-NG and Juniper Devices – Pimping your KVM

Have you ever noticed that your vSRX, vMX and vQFX run on insane CPU percentage?
Well yes, you might think because on DPDK Hosts (I wrote about that earlier), the v-Devices run in “Poll-Mode”. But that doesn’t mean, you can’t try to “improve” this behavior.

CAUTION: I tried this myself and have not seen any issues so far – however, this does not guarantee fatal possible side-effects, that I’m unaware of or that do not affect my Labs. If you mess with your EVE, you are on your own so try it and if it works fine, if not you should probably change it back or wait for the official release from the EVE-NG Team if this turns out to be working and they feel the need to implement this. I only tried this with “Pure-Juniper” Labs so far.

In my Test-Setup (1 vMX and 2 vQFX) my CPU went from 35% to below 16% (EVE on ESX).
I think Bare (which I will try next) will show the same if not more drops in the CPU usage.

Update 02.09.2019 – Yes. Bare was even more crazy, allowing me to run 40vQFX at the same time at roughly 70% CPU usage!!!! Insane :O

Also, there was no need to reboot the host.

After the config-knob

Here’s what I changed:


Let me know in the comments or on Twitter if this also worked for you and if you see any side effects please also let me know.

Heres some background in case you wonder, what this does:
The interesting Part for me was the Notes at the end:

Sounds like the v-Devices, right? 😉

6 thoughts on “EVE-NG and Juniper Devices – Pimping your KVM

  1. E.V.

    Hi Christian.

    I’ve been looking to get into Juniper and saw your blog. I had a question about setting up Juniper images in EVE. Are you also installing licenses on the vMx images, or will you have limited functionality to do basic testing without the needs of licenses? I see there are evaluation 60-day licenses, so I was just wondering if it was necessary to keep getting these licenses every 60-days to run the images or not.

    Thank you!

    1. christianscholz Post author

      Hi E.V.

      this depends actually what I want to try.
      For most of the scenarios I need the 60-day advanced Test License.
      After 60 days, you can always “wipe” your vMX, giving you another 60 days (just re-paste your config and license and you’re done).


      1. E.V.

        Thank you so much Christian! That’s great to know you can just re-use the license by wiping out the image and re-installing a new one.

  2. networkjitter

    Hi Christian,

    Thanks for the great post. I configured this too in my lab (EVE on ESXi) and saw significant reduction in CPU utilization. Since posting this, have you noticed any side effects from the change? Also I’m curious to know what version of vQFX you’re running in your lab and what resource (vCPU, memory) allocations you’re using. I’m currently running 18.4R1 and EVE defaults to the following which seems generous IMO.

    vQFX RE: 2 vCPU, 2G RAM
    vQFX PFE: 2 vCPU, 4G RAM


  3. James

    Hi Christian

    I just tried this (10 VMX (Junos 14, single image version)… On my server this setup (all sitting at amnesiac) was idle at 14%.. After the changes, it’s idle at 19% 😀

    Maybe those older ones don’t use DPDK?

    1. christianscholz Post author

      Hi James,

      thats odd 😀
      I never saw that behavior, but I also don’t use 14 anymore because of all the EVPN Improvements in 18.x


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