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1608 discussions

CentOS7, Xen 4.6.1, kernel 3.18.25-19 strange performance problem
by T.Weyergraf 11 Apr '16

11 Apr '16

Hi all, i just stumbled over a strange performance issue with my Xen setup. I use centos-virt Xen since a long time on my workstation and usually never check performance. However, yesterday I booted into the 3.18.25-19 Dom0 kernel *without* Xen and found the system noticably more responsive. That triggered me into running a simple kernel compile benchmark and compare the results: Testsequence: echo 3 > /proc/sys/vm/drop_caches make distclean cp ../.config . #copies an existing valid config for compile make oldconfig time make -j <threads> bzImage Results: xen 4.6.1 - kernel 3.18.25-19 16 threads: real 1m41.983s user 16m37.247s sys 5m7.121s 32 threads: real 1m29.240s user 23m7.170s sys 6m31.497s kernel 3.18.25-19 16 threads: real 1m12.909s user 14m37.627s sys 1m36.521s 32 threads: real 1m0.530s user 18m45.569s sys 1m58.807s Some notes: - System is a HP z840 with 2*8core E5 v3 Xeon and 128gig Ram. Disk is an Intel 750 ssd (PCIe nvme) - While normally in Xen, I limit Dom0 Memory via dom0_mem, but for the tests, Dom0 was allowed to use full memory - While running the test, no guest was running except Dom0. System was booted to graphical desktop and was completely unloaded otherwise - (boot-)logs showed no issues with ACPI or hardware-support or whatsoever. I have not yet run any in-depth investigation or tried too many different settings, but I find the differences quite noteworthy. So, if anybody came across the same issues, has some hints or suggestions, feel free. I'll continue poking around and if there is interest, i'll post updates. Regards, Thomas

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systemd-nspawn will replace lxc
by C. L. Martinez 11 Apr '16

11 Apr '16

Hi all, It seems RH will deprecate LXC (https://access.redhat.com/articles/1365153) and will go to docker way (or maybe I am totally wrong). Is this true?? Will be systemd-nspawn a lightweight replacement for LXC containers?? Thanks. -- Greetings, C. L. Martinez

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(qemu-kvm-ev) parallel port forwarding to guest VM
by Subscriber 11 Apr '16

11 Apr '16

Hi Where can I find information on supported devices in qemu-kvm-ev? Does it support parallel port forwarding to the guest VM? Thx. P.S. cat /etc/redhat-release CentOS Linux release 7.2.1511 (Core)

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High Guest CPU Utilization when using libgfapi
by qingwei wei 11 Apr '16

11 Apr '16

Hi, I am currently testing running Openstack instance on Cinder volume with libgfapi. This instance is the Windows instance and i found that when running random 4k write workload, the CPU utilization is very high, 90% CPU utilization with about 86% in privileged time. I also tested the workload with volume from NFS and the CPU utilization is only around 5%. For gluster fuse, the CPU utilization is also not as high as 90%, around 30-40%. Is there any reason why is that so? Appreciate on any comments and suggestions. Details. Workload generator: IOMeter Instance: Windows 2008R2 Openstack Host: CentOS 7 qemu-kvm version: qemu-kvm-ev-2.1.2-23.el7.1.x86_64 Workload: 4kb random write, 4 workers with each worker configure to have 4 outstanding IOs Gluster server and client version: 3.7.8 Gluster info Volume Name: g37test Type: Distribute Volume ID: 27947421-111b-4727-bcaf-bafe73debe07 Status: Started Number of Bricks: 1 Transport-type: tcp Bricks: Brick1: 192.168.99.4:/mnt/ssd/g37test Options Reconfigured: performance.readdir-ahead: on nfs.disable: true performance.io-cache: off performance.quick-read: off server.allow-insecure: on storage.owner-uid: 165 storage.owner-gid: 165 Cw

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CentOS 6
by Gene 08 Apr '16

08 Apr '16

Will Xen4Centos on CentOS 6 be supported all the way through its EOL (November 30th, 2020)? If not when will it stop being supported/updated under this SIG? Thanks. -Gene

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New qemu-kvm-ev available for testing
by Sandro Bonazzola 08 Apr '16

08 Apr '16

Hi, qemu-kvm-ev-2.3.0-31.el7_2.10.1 has been tagged for testing. In order to test it, please enable centos-qemu-ev-test repository after installing centos-release-qemu-ev Thanks, -- Sandro Bonazzola Better technology. Faster innovation. Powered by community collaboration. See how it works at redhat.com

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xen-4.4.4-2.el6 packages added to virt6-xen-44-testing
by Johnny Hughes 07 Apr '16

07 Apr '16

All, I have upgraded xen-44 from Xen-4.4.3 to Xen-4.4.4 (and placed the resulting RPMs from xen-4.4.4-2.el6.src.rpm into virt6-xen-44-testing). These RPMs have all the latest updates that were rolled into the xen-4.4.3-14.el6.src.rpm packages (through XSA-172 updates). Here is how to test: 1. If you want this box to always have 'testing' enabled for xen-44 .. do this: Edit /etc/yum.repos.d/CentOS-Xen-44.repo and set 'Enabled=1' in the [centos-virt-xen-44-testing] and then do: yum update (In this case, the testing repo remains enabled) 2. If you would rather not turn on testing permanently, but just want to test these updates (and leave only the main repo enabled by default), then do this: yum --enablerepo centos-virt-xen-44-testing update ============== The above assumes you have followed George's instructions and have removed centos-release-xen and centos-rtelease-xen-46 and have installed centos-release-xen-44 to stay on the Xen-4.4 branch, and have not upgraded to Xen-4.6. Thanks, Johnny Hughes

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Xen custom vifname
by Peter Braun 05 Apr '16

05 Apr '16

Hi, Centos 7 Xen4CentOS - 4.6.1 Open vSwitch When i specify custom name of the domU NIC than it refues to start vif = [ 'vifname=vNIC1' ] libxl: error: libxl_exec.c:118:libxl_report_child_exitstatus: /etc/xen/scripts/vif-openvswitch online [10168] exited with error status 1 libxl: error: libxl_device.c:1084:device_hotplug_child_death_cb: script: ip link set vif38.0 name vNIC1 failed libxl: error: libxl_create.c:1381:domcreate_attach_vtpms: unable to add nic devices libxl: error: libxl.c:1591:libxl__destroy_domid: non-existant domain 38 libxl: error: libxl.c:1549:domain_destroy_callback: unable to destroy guest with domid 38 libxl: error: libxl.c:1476:domain_destroy_cb: destruction of domain 38 failed When removed the vifname settings the domU starts just fine. vif = [ '' ] Same error when used wi classic Bridge for networking. Is vifname setting still supported? On CentOS5 & Xen 3.4 this parameter works just fine. Regards

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Reminder: Virt SIG meeting at 3pm BST (2pm UTC) today on #centos-devel
by George Dunlap 05 Apr '16

05 Apr '16

Reminder that (at least for the moment), unlike many of the other meetings, our meeting is on British time at 3pm. -George

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status for centos-release-docker and docker packages
by Lokesh Mandvekar 31 Mar '16

31 Mar '16

I have rpm sources for centos-release-docker at https://github.com/CentOS-virt7/centos-release-docker Some updated packages available on centos-docker-common-testing branch are: docker: http://cbs.centos.org/koji/buildinfo?buildID=9932 atomic: http://cbs.centos.org/koji/buildinfo?buildID=10046 docker-distribution: http://cbs.centos.org/koji/buildinfo?buildID=9950 I think I need to have the docker testing packages available on buildlogs.c.o. That's probably a task for kb, arrfab? Let me know what next. -- Lokesh Freenode: lsm5 GPG: 0xC7C3A0DD

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