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)
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)
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)
--
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Christoph -
Pasi Kärkkäinen