Re: Bad performance of virtual disk driver

[Manuel Bouyer <bouyer%antioche.lip6.fr@localhost>]

On Sun, May 22, 2005 at 12:55:58AM +0200, Rainer Brinkmöller wrote:
> Hello Matthias,
> 
> i did try the same test you did by the following setup in my environment:
> 
> Hypervisor:        Xen 2.0.5
> domain0:            NetBSD 3.0_BETA (binarys from 2005-04-08)
> domain1:            NetBSD 3.0_BETA (binarys from 2005-04-08)
> doamin2:            NetBSD 3.0_BETA (binarys from 2005-04-08)
> 
> i've got the following output in domain0:
> 
> # dd if=/tmp/testfile of=/dev/null bs=1024k
> 455+1 records in
> 455+1 record out
> 477170189 bytes transferred in 8.439 secs (56543451 bytes/sec)
> 
> and the output of domain2 was:
> 
> # dd if=/tmp/testfile of=/dev/null bs=1024k
> 455+1 records in
> 455+1 record out
> 477170189 bytes transferred in 13.024 secs (36637760 bytes/sec)

Note that performances also depend on the place of the file on disk.
The closer to sector 0, the faster. So if domain0's /tmp is in partition a
which is on the start of the disk, it will be faster than in domain2's if
domain2's partition is near the end.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--