Re: Bad performance of virtual disk driver

[Matthias Scheler <tron%zhadum.de@localhost>]

On Tue, May 03, 2005 at 02:34:56PM +0100, Matthias Scheler wrote:
> I've using the following setup:
> 
> Hypervisor:   Xen 2.0.5
> dom0:         Linux 2.6.10
> domU:         NetBSD 3.0_BETA (sources from 2005-04-28)
> 
> The performace of the virtual disks is very bad ...
> 
>       # dd if=/dev/xbd1b of=/dev/null bs=1024k
>       512+0 records in
>       512+0 records out
>       536870912 bytes transferred in 331.800 secs (1618055 bytes/sec)
> 
> ... compared to the performance in the Linux dom0:
> 
>       # dd if=/dev/vg/matthias-1swap of=/dev/null bs=1024k
>       512+0 records in
>       512+0 records out
>       536870912 bytes transferred in 15.469114 seconds (34705990 bytes/sec)

Performance in an unpriviliged Linux domain on the same machine ...

        # dd if=/dev/sda2 of=/dev/null bs=1024k
        200+0 records in
        200+0 records out
        209715200 bytes transferred in 20.675648 seconds (10143102 bytes/sec)

... is also slower than in the Linux dom0:

        # dd if=/dev/vg/jds3swap of=/dev/null bs=1024k
        200+0 records in
        200+0 records out
        209715200 bytes transferred in 5.931684 seconds (35355086 bytes/sec)

But here it is only by a factor of 3 and not 20.

        Kind regards

-- 
Matthias Scheler                                  http://scheler.de/~matthias/