[kernel-xen] Centos7 Dom0 IO performance

[Glenn Enright]

You may want to look at tweaking which scheduler you are using. Also 
look at the the blkfront drive options eg the command line passed to 
each domU, like extra="elevator=noop xen-blkfront.max=64"

Regards, Glenn
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On 08/31/15 15:51, Christoph Kaminski wrote:
> 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...
>
> Am 2015-08-30 10:21, schrieb Christoph Kaminski:
>> Hi all...
>>
>> 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
>>
>> 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?
>>
>> (I use the xen45 pkgs)
>>
>> TiA
>