host-passthrough or pcid enable for Westmere and SandyBridge
Hi, With the meltdown patches, now it is specially beneficial to have the pcid feature in the virtual CPUs. See: https://groups.google.com/forum/#!topic/mechanical-sympathy/L9mHTbeQLNU The PCID feature is available in physical "Westmere" (Release date circa 2010) or newer CPUs. However, in libvirt the pcid feature is only avalilable for virtual CPUs Haswell (Release date circa 2013) or newer. The recomendation is using Haswell, Broadwell or Skylake based model or host passthrough. Now, I think "host passthrough" is not an option for oVirt for good reason so this leaves Haswell, Broadwell or Skylake as options. Is it possible to edit /usr/share/libvirt/cpu_map.xml on the compute nodes to add the pcid feature to the virtual CPU models between Westmere and Haswell (that would be Westmere and SandyBridge)? Is anyone aware if something like this is being considered by the libvirt developers? Actually understanding the implications or doing so is way beyond my skill level. By now you may have guessed that my oVirt clusters use physical Westmere and SandyBridge CPUs :-/ Thanks in advance for your help! -- Eduardo Mayoral Jimeno (emayoral@arsys.es) Administrador de sistemas. Departamento de Plataformas. Arsys internet. +34 941 620 145 ext. 5153
Hi, are there any news on this? I tried to change /usr/share/libvirt/cpu_map.xml manually and added pcid flag to SandyBridge CPU and restarted HW node, but on VM, nothing changed. I found the xml file for this VM and I found a strange content: In /var/run/libvirt/qemu/, there are the XML files of the running VMs -> ... <cpu mode='custom' match='exact' check='full'> <model fallback='forbid'>SandyBridge</model> <topology sockets='16' cores='1' threads='1'/> <feature policy='require' name='vmx'/> <feature policy='require' name='vme'/> <feature policy='disable' name='pcid'/> <feature policy='require' name='hypervisor'/> <feature policy='require' name='arat'/> <feature policy='require' name='xsaveopt'/> ... -> feature policy='disable' name='pcid' It was indeed added to XML file, but it looks like it is somehow disabled. I actually don't know, how to enable it. On hosts, where cpu_map.xml is not changed, this entry is not there. We are running version 4.1.7 BR Florian -------------------------------------------------------------------------------------------------------------------- UBIMET GmbH - weather matters Ing. Florian Schmid • IT Infrastruktur Austria A-1220 Wien • Donau-City-Straße 11 • Tel +43 1 263 11 22 DW 469 • Fax +43 1 263 11 22 219 fschmid@ubimet.com • www.ubimet.com • Mobile: +43 664 8323379 Sitz: Wien • Firmenbuchgericht: Handelsgericht Wien • FN 248415 t -------------------------------------------------------------------------------------------------------------------- The information contained in this message (including any attachments) is confidential and may be legally privileged or otherwise protected from disclosure. This message is intended solely for the addressee(s). If you are not the intended recipient, please notify the sender by return e-mail and delete this message from your system. Any unauthorized use, reproduction, or dissemination of this message is strictly prohibited. Please note that e-mails are susceptible to change. UBIMET GmbH shall not be liable for the improper or incomplete transmission of the information contained in this communication, nor shall it be liable for any delay in its receipt. UBIMET GmbH accepts no liability for loss or damage caused by software viruses and you are advised to carry out a virus check on any attachments contained in this message. ----- Ursprüngliche Mail ----- Von: "Eduardo Mayoral" <emayoral@arsys.es> An: "users" <users@ovirt.org> Gesendet: Donnerstag, 11. Januar 2018 07:56:56 Betreff: [ovirt-users] host-passthrough or pcid enable for Westmere and SandyBridge Hi, With the meltdown patches, now it is specially beneficial to have the pcid feature in the virtual CPUs. See: https://groups.google.com/forum/#!topic/mechanical-sympathy/L9mHTbeQLNU The PCID feature is available in physical "Westmere" (Release date circa 2010) or newer CPUs. However, in libvirt the pcid feature is only avalilable for virtual CPUs Haswell (Release date circa 2013) or newer. The recomendation is using Haswell, Broadwell or Skylake based model or host passthrough. Now, I think "host passthrough" is not an option for oVirt for good reason so this leaves Haswell, Broadwell or Skylake as options. Is it possible to edit /usr/share/libvirt/cpu_map.xml on the compute nodes to add the pcid feature to the virtual CPU models between Westmere and Haswell (that would be Westmere and SandyBridge)? Is anyone aware if something like this is being considered by the libvirt developers? Actually understanding the implications or doing so is way beyond my skill level. By now you may have guessed that my oVirt clusters use physical Westmere and SandyBridge CPUs :-/ Thanks in advance for your help! -- Eduardo Mayoral Jimeno (emayoral@arsys.es) Administrador de sistemas. Departamento de Plataformas. Arsys internet. +34 941 620 145 ext. 5153 _______________________________________________ Users mailing list Users@ovirt.org http://lists.ovirt.org/mailman/listinfo/users
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Eduardo Mayoral -
Florian Schmid