[CentOS-virt] poor performance with dom0 on centos7

Christoph mangel at gmx.de
Tue Sep 1 04:47:18 UTC 2015


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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Greetz


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