On Wed, Sep 16, 2015 at 09:46:52PM +0200, Christoph wrote: > Hi > Hi, > Im now pretty sure the problem is the DomU with NFS Server. > > If I write on a NFS share from other Host (bare metal or other vm) > then I see on my NFS server nearly the whole time 100% io at > [jbd2/dm-5-8] process... > If I write on a SMB share (same partition as nfs share) from other > Host then it is a little bit better but still ever and ever again > 100% io load > Are you using nfs over UDP or TCP ? > If I write a 1GB file on the same partition (with nfs/samba share) > with dd, I dont see the high io load... > > Is there a known problem with nfs/smb shares and/or dm in xen domU's > on centos 7 as dom0? With centos 6 as dom0 I didnt had the > problem... > (the partition with the shares is a raid5 software partition, soft > raid is build in dom0 and as a xvd device passed through to the domU > with the shares) > > could selinux be the problem? I have it in permissive mode on all > hosts here (dom0 and domU) not disabled... > I don't think. > Any hints for me? > If you used NFS over UDP, try running it over TCP. What does 'top' and/or 'iostat -x 1' say during the 'benchmark' ? -- Pasi > Am 2015-09-01 06:47, schrieb Christoph: > >Hi All > > > >it is possible to tune dom0/domU for better IO/network performance? > >Since I have changed to Cenots7 dom0, I have a really poor IO > >performance inside a PV VM. > > > >I have already done what is described on > >http://wiki.xenproject.org/wiki/Tuning_Xen_for_Performance > >It is better now but still significantly worse than with centos6 dom0 > > > >my settings: > > > >xen parameter: dom0_mem=1024M cpufreq=xen dom0_max_vcpus=2 > >dom0_vcpus_pin > > > >xl sched-credit > >Cpupool Pool-0: tslice=30ms ratelimit=1000us > >Name ID Weight Cap > >Domain-0 0 1024 0 > >samael 1 256 0 > >satan 2 512 0 > >amon 3 256 0 > >leviathan 4 512 0 > > > >echo 1048576 > /proc/sys/net/ipv4/tcp_limit_output_bytes on dom0 > > > >the both domU's satan and leviathan are very IO performance oriented > >(NFS server and downloading vm) > > > >Is there something more what I can do or try? > > > >could it be a selinux issue? I have it in permissive mode there, not > >disabled. But permissive means only to collect the info not enforcing > >the rules... > > > >(I use the xen45 pkgs) > > -- > ------ > Greetz > _______________________________________________ > CentOS-virt mailing list > CentOS-virt@xxxxxxxxxx > https://lists.centos.org/mailman/listinfo/centos-virt _______________________________________________ CentOS-virt mailing list CentOS-virt@xxxxxxxxxx https://lists.centos.org/mailman/listinfo/centos-virt
