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
On Tue, Sep 01, 2015 at 06:47:18AM +0200, Christoph wrote:> Hi All >Hello,> 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) >You forgot to mention the most important thing.. what kind of performance numbers are you seeing? What are you expecting? Thanks, -- Pasi
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 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... Any hints for me? 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
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 at centos.org > https://lists.centos.org/mailman/listinfo/centos-virt