Re: [Xen-devel] Read Performance issue when Xen Hypervisor is activated

[Michael Schinzel <schinzel@xxxxxxxxxxxxxx>]

Ok, it seems there is no way to Upgrade the Intel ME Version. In the lates BIOS 
Version of Supermicro it is 

-------[ ME Analyzer v1.7.0_35 RC ]-------
            Database r75_3

File:     X9DRi5.709

Firmware: Intel SPS
Version:  02.01.07.231.1
Release:  Production
Type:     Region
Mode:     Dual OPR
Date:     10/05/2013
Size:     0x2F0000

Also i dont know, if this is realy the issue. Because with a non Hypervisor 
Kernel it work all fine. 


Mit freundlichen Grüßen

Michael Schinzel
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-----Ursprüngliche Nachricht-----
Von: Dario Faggioli [mailto:dario.faggioli@xxxxxxxxxx] 
Gesendet: Freitag, 30. Dezember 2016 17:35
An: Michael Schinzel <schinzel@xxxxxxxxxxxxxx>; Xen-devel 
<xen-devel@xxxxxxxxxxxxxxxxxxxx>
Cc: Roger Pau Monne <roger.paumonne@xxxxxxxxxx>; Bob Liu <bob.liu@xxxxxxxxxx>
Betreff: Re: [Xen-devel] RE: Read Performance issue when Xen Hypervisor is 
activated

[Cc-ing someone which have done disk benchmark in somewhat recent time]

On Tue, 2016-12-27 at 14:26 +0000, Michael Schinzel wrote:
> We have searched in the last days more and more for the cause of this 
> performance issue.
>  
> In cooperation with the datacenter, we change some hardware to check, 
> if the problem already proceeds. We put the RAID Controller included 
> all RAID Arrays to another Supermicro Mainboard: X10SLM-F with only 
> one CPU. The result was, we got 400 MB/s read Speed. So it seems there 
> is an issue with the Servers Mainboard / CPU and the Xen Hypervisor 
> but, we also change the Mainboard to an Supermicro X9DR3-F with the 
> actual BIOS Version 3.2a – these also do not solved the problem with 
> the performance.
>  
> What we also have done:
> -          Upgraded Hypervisor from default Debian 8 – 4.4.1 to 4.8.
> -          Tested some kernel boot configurations\
>
I think it would be useful to know more about your configuration, e.g., are 
these tests being done in Dom0? How many vCPUs and memory does Dom0 have?

> With an non hypervisor Kernel, the system also uses the read Cache of 
> the controller and after some read operations at the same file, it 
> gets 1.2 G/s back from the Cache. At Xen Hypervisor Kernel, it seems 
> the system do not use any caching operations. I also tested a bit with 
> hdparm:
>  
> root@v7:~# hdparm -Tt /dev/sdb
>  
> /dev/sdb:
> Timing cached reads:   14060 MB in  1.99 seconds = 7076.16 MB/sec 
> Timing buffered disk reads: 304 MB in  3.01 seconds = 100.85 MB/sec
>  
> This Performance is horrable. It is a RAID 10 with read/write cache 
> and SSD Caching functions.
>  
> Does somebody know how Xen proceeds with such Caching Systems?
>  
>  
> Yours sincerely
>  
> Michael Schinzel
--
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, 
Citrix Systems R&D Ltd., Cambridge (UK)
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