I''ve got a Debian Lenny Dom0 with Debian''s 2.6.26 Xen
paravirt_ops kernel
and a Debian Lenny DomU. xen-hypervisor is Debian''s 3.2.1 package. The
dom0 has two dual core Opteron CPUs without hardware virtualisation
support.
In the domU I/O performance is very bad. In the dom0, I get about 46 MB/s:
# dd if=/dev/zero of=/root/zeroes bs=20M count=20
20+0 records in
20+0 records out
419430400 bytes (419 MB) copied, 9.12234 s, 46.0 MB/s
While the domU only gets 6:
Last login: Tue Oct 14 07:46:10 2008 from 192.168.0.129
# dd if=/dev/zero of=/root/zeroes bs=20M count=20
20+0 records in
20+0 records out
419430400 bytes (419 MB) copied, 70.1395 s, 6.0 MB/s
The domU only has 384 MB of RAM, while the dom0 has 4 GB, but as almost
nothing is running in the domU and its cache is pretty big, I doubt this
can explain this enormous difference in I/O performance:
# free
total used free shared buffers cached
Mem: 393432 366800 26632 0 2420 328444
-/+ buffers/cache: 35936 357496
Swap: 131064 20 131044
Both the dom0 and domU are using the ext3 file system on LVM logical
volumes on a 3Ware hardware RAID 5.
Any idea what I could try to improve the performance?
--
Frederik Himpe
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tap or loop? On Tue, 14 Oct 2008, Frederik Himpe wrote:> I''ve got a Debian Lenny Dom0 with Debian''s 2.6.26 Xen paravirt_ops kernel > and a Debian Lenny DomU. xen-hypervisor is Debian''s 3.2.1 package. The > dom0 has two dual core Opteron CPUs without hardware virtualisation > support. > > In the domU I/O performance is very bad. In the dom0, I get about 46 MB/s: > > # dd if=/dev/zero of=/root/zeroes bs=20M count=20 > 20+0 records in > 20+0 records out > 419430400 bytes (419 MB) copied, 9.12234 s, 46.0 MB/s > > While the domU only gets 6: > > Last login: Tue Oct 14 07:46:10 2008 from 192.168.0.129 > > # dd if=/dev/zero of=/root/zeroes bs=20M count=20 > 20+0 records in > 20+0 records out > 419430400 bytes (419 MB) copied, 70.1395 s, 6.0 MB/s > > The domU only has 384 MB of RAM, while the dom0 has 4 GB, but as almost > nothing is running in the domU and its cache is pretty big, I doubt this > can explain this enormous difference in I/O performance: > > # free > total used free shared buffers cached > Mem: 393432 366800 26632 0 2420 328444 > -/+ buffers/cache: 35936 357496 > Swap: 131064 20 131044 > > Both the dom0 and domU are using the ext3 file system on LVM logical > volumes on a 3Ware hardware RAID 5. > > Any idea what I could try to improve the performance? > > -- > Frederik Himpe > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
On Tue, Oct 14, 2008 at 10:27:00AM +0200, Stefan de Konink wrote:> tap or loop?the domU disk is a logical volume, it''s not a file based disk. -- Frederik Himpe _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users