On 6/15/20 5:40 PM, Stephen John Smoogen wrote: > > > On Mon, 15 Jun 2020 at 09:42, Manuel Wolfshant > <wolfy at nobugconsulting.ro <mailto:wolfy at nobugconsulting.ro>> wrote: > > On 6/15/20 2:46 PM, Stephen John Smoogen wrote: > > I got inspired by Adi's earlier suggestion and after reading > https://access.redhat.com/articles/3311301 I've tried today all > variants of disabling the spectre mitigations. Whatever I do, > immediately after a reboot, yum reinstall kernel does not take > less than 5 minutes :( It goes down to 2 min if I repeat the > operation afterwards so I guess some caching kicks in. I will try > later today the kernels from elrepo and maybe even xen.crc.id.au > <http://xen.crc.id.au> ( I kind of hate the "disable selinux" > recommendation from the install page so I postponed it in the hope > of other solution ). > > > > If you can do a full reinstall, could you see if a KVM host/guest > combo has the same problem? That would at least point the finger more > firmly at VT, spectre or something else. > > I finally managed to install a fresh KVM host / guest pair on an identical blade ( HS21XM, 64 GB ram, 2*E5450@ 3.00GHz ). Here are the results I see: 1. KVM host, stock instalation and fully updated, kernel 3.10.0-1127.10.1 #cd /sys/kernel/debug/x86/ #cat ibrs_enabled pti_enabled retp_enabled 0 1 1 #time yum -y reinstall kernel-3.10.0-1127.el7.x86_64 real 0m50.026s user 0m32.872s sys 0m23.312s 2. KVM guest on the same machine (virt-install --name guest1-rhel7 --memory 2048 --vcpus 2 --disk size=20 --network=bridge:br0 --pxe --os-variant rhel7 <=== copy/paste from https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/virtualization_deployment_and_administration_guide/sect-guest_virtual_machine_installation_overview-creating_guests_with_virt_install ), stock installation and fully updated with absolutely no change towards the defaults including same ibrs_enabled pti_enabled retp_enabled as the host, , kernel 3.10.0-1127.10.1 #time yum -y reinstall kernel-3.10.0-1127.el7.x86_64 real 2m39.644s user 1m54.662s sys 1m32.496s 3. Xen Domu, 3.10.0-1127.8.2.el7.x86_6 ( but results are consistent across all kernels ) # cat ibrs_enabled pti_enabled retp_enabled 0 0 0 # time yum -y reinstall kernel-3.10.0-1127.el7.x86_64 real 5m44.030s user 2m9.931s sys 4m7.771s 4. Dom0, 4.9.215-36.el7.x86_64, , xen 4.12 from centos' repo # time yum -y reinstall kernel-3.10.0-1127.el7.x86_64 real 1m52.417s user 0m45.704s sys 1m32.167s -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.centos.org/pipermail/centos-virt/attachments/20200618/fe5d83b9/attachment-0005.html>