Re: [Xen-users] Difference performances between HVM and PV guest

On Sun, May 24, 2009 at 7:25 PM,  <helicoterus-elih@xxxxxxxx> wrote:
>
> I perform some tests to get hard disc performance differences between HVM 
> domU and a paravirtualized one (both Debian Lenny).

first of all, make sure you do NOT use file:/ in domU config. At least
use tap:aio:

> I used hdparm ( option -t and -T) to test cache of disc and disc sequential 
> read.
> Syntax is:
> hdparm -t|-T /dev/hda1
>
> hdparm -t for hvm returns about 30 MB/sec, wheras hdparm -t for PV return 
> about 180 MB/sec.

This is normal. HVM by default should have MUCH lower disk throughput.
That's why HVM domUs need PV drivers for both Linux (included by
default on RHEL/Centos 5.3, not available yet for newer kernels) and
Windows (like GPLPV).

> hdparm -T for hvm returns about 1247 MB/sec, wheras hdparm -T for PV return 
> about 1183 MB/sec.

-T is cached result. Repeat this several times and you should find
similar output for both PV and HVM.

-- 
Fajar

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users

<Prev in Thread]

Current Thread

[Next in Thread>

Previous by Date:

[Xen-users] lvm, mattias

Next by Date:

[Xen-users] how to set 'extra' parameter of xen configuration file?, Turinglifer Chu

Previous by Thread:

[Xen-users] Difference performances between HVM and PV guest in hard disc reading, helicoterus-elih

Next by Thread:

Re: [Xen-users] Difference performances between HVM and PV guest in hard disc reading, Heli

Indexes:

[Date] [Thread] [Top] [All Lists]