Posts

• RE: XCP-ng 8.3 updates announcements and testing

  Thanks everyone for testing! As you can all see here, it’s been extremely useful

  posted in News

  O

  olivierlambert
  
• RE: XCP-ng 8.3 updates announcements and testing

  The storage and XAPI teams are currently investigating the issues that have been reported.

  There is no final solution yet, but we are getting closer. Unfortunately, there is no ETA at this time.

  Thank you very much for all your testing and feedback!

  posted in News

  G

  gduperrey
  
• Enabling Intel APICv for better performance

  Consider this feature as experimental

  Many Intel CPUs have support for Intel APICv (APIC Virtualization) features that aims at reducing the number of APIC-related VM-Exits in guests, hence improving performance.
  This has been introduced circa Intel Ivy Bridge-EP, and is also available on somewhat recent client CPUs as well. But keep in mind that not all SKUs have support for it.

  Xen has support for it since roughly Xen 4.3, yet XenServer (and XCP-ng) originally disabled by default due to issues at this time around live migration between hardware that supports it and ones that don't.

  Internal testing on the feature shows performance improvements in various benchmarks (5-10% in I/O benchmarks up to 30% on nginx with a Ice Lake Xeon). We didn't test on other CPUs, but older CPUs (in particular those affected by L1TF/Foreshadow) may observe larger improvements.

  How to enable

  This feature exists in the Xen version shipped in XCP-ng, but disabled by default, you can enable support on the host with

  /opt/xensource/libexec/xen-cmdline --set-xen apicv=1
  # then reboot
  

  Once enabled, you can check hardware support with

  xl dmesg | grep -A 25 "VMX: Supported advanced features"
  

  And look for APIC Register Virtualization and Virtual Interrupt Delivery.

  The feature can be disabled with

  /opt/xensource/libexec/xen-cmdline --delete-xen apicv
  # then reboot
  

  What to test

  Along with general feedback on the feature (does it work, supported hardware, ...), we're interested on :

  • interactions with live migration, especially with hosts that have different configuration of APICv
  • performance on various workloads (web server, databases, I/O, ...)

  What about AMD ?

  AMD counterpart is AVIC (Advanced Virtualized Interrupt Controller) introduced (in practice) with Zen 2 (but also existed on some Carrizo CPUs) then improved with x2AVIC with Zen 4.
  Xen support for (x2)AVIC is currently work in progress.
  Refer to Denis Mukhin's presentation on AVIC for Xen (Xen Summit 2026) : https://youtu.be/RhaJsOU_PIA

  posted in Development

  T

  TeddyAstie
  
• RE: XCP-ng 8.3 updates announcements and testing

  @flakpyro Hello,

  It would be preferred to use another method.
  You can use the resetvdis.py script in the /opt/xensource/sm/ to reset values instead,
  using vdi-forget is unadvised in this case, it can cause issues by losing information that are stored in XAPI about VDIs.

  /opt/xensource/sm/resetvdis.py single <VDI UUID>
  

  posted in News

  D

  dthenot
  
• RE: XCP-ng 8.3 updates announcements and testing

  Some message formats changed between the two releases, so VMs started before the update (with an 11.3 tapdisk and tapback) can’t understand some of the changed commands. Rebooting XCP-ng or doing an RPU should work. Since not every command is affected, restarting tapback is usually enough: systemctl restart tapback.service
  We're going to work to avoid that.

  posted in News

  E

  Emmanuel V
  
• RE: Support for newer Emulex LPe37xxx amd LPe36xxx Fiber channel adapters on XCP-ng 8.3 - your testing is needed

  @jr-m4 thank you so much for testing this updated driver.

  Just to make sure, I understand now that you confirm the driver is working as expected and the issues you had were not related to it? Or are there any problems still with this new driver?

  Many thanks again for spending the time to test and report.

  posted in Hardware

  M

  MrQ