Xen PVHVM with FreeBSD10 Guest

[Sydney Meyer]

Well then, thanks for the hint.. dmesg shows the following:

Jan 16 18:22:30 bsd10 kernel: xn0: <Virtual Network Interface> at device/vif/0 on xenbusb_front0
Jan 16 18:22:30 bsd10 kernel: xn0: Ethernet address: 00:16:3e:df:1b:5a
Jan 16 18:22:30 bsd10 kernel: xenbusb_back0: <Xen Backend Devices> on xenstore0
Jan 16 18:22:30 bsd10 kernel: xn0: backend features: feature-sg feature-gso-tcp4
Jan 16 18:22:30 bsd10 kernel: xbd0: 8192MB <Virtual Block Device> at device/vbd/768 on xenbusb_front0
Jan 16 18:22:30 bsd10 kernel: xbd0: attaching as ada0
Jan 16 18:22:30 bsd10 kernel: xbd0: features: flush, write_barrier
Jan 16 18:22:30 bsd10 kernel: xbd0: synchronize cache commands enabled.

Now i did some tests with raw images and the disk performs very well (10-15% less than native throughput).

Is this a known problem or maybe specific to this constellation?

The Test System is running on a Haswell Intel Core i3 CPU (4310T) with an Intel H81 Chipset.

Cheers,
Sydney.

On 16.01.2014, at 18:06, Sydney Meyer <meyer.sydney at googlemail.com> wrote:

> No, the VMs are running on local LVM Volumes as Disk Backend.
> 
>> On 16 Jan 2014, at 17:59, Roger Pau Monné <roger.pau at citrix.com> wrote:
>> 
>>> On 16/01/14 17:41, Sydney Meyer wrote:
>>> Hello everyone,
>>> 
>>> does someone know how to check if the paravirtualized I/O drivers from Xen are loaded/working in FreeBSD 10? To my understanding it isn't necessary anymore to compile a custom kernel with PVHVM enabled, right? In /var/log/messages/ I can see the XN* and XBD* devices and the network performance is very good (saturated Gb) compared to qemu-emulated, but the disk performance is not as well, infact, it is even slower than emulated with qemu (0.10.2). I did some test with dd and bonnie++, turned caching on the host off and tried to directly sync to disk, PVonHVM is averagely 15-20 % slower than QEMU at throughput. Both VM's are running on the same host on a Xen 4.1 Hypervisor with QEMU 0.10.2 on a Debian Linux 3.2 Kernel as Dom0.
>> 
>> PV drivers will be used automatically if Xen is detected. You should see
>> something like this on dmesg:
>> 
>> xn0: <Virtual Network Interface> at device/vif/0 on xenbusb_front0
>> xn0: Ethernet address: 00:16:3e:47:d4:52
>> xenbusb_back0: <Xen Backend Devices> on xenstore0
>> xn0: backend features: feature-sg feature-gso-tcp4
>> xbd0: 20480MB <Virtual Block Device> at device/vbd/51712 on xenbusb_front0
>> xbd0: features: flush, write_barrier
>> xbd0: synchronize cache commands enabled.
>> 
>> Are you using a raw file as a disk?
>> 
>> Roger.
>>