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?


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