Hi,
I'm trying to make use of 9p folder sharing under libvirt/QEMU.
Unfortunately, 9p seems to be painfully slow.
Below please find my test results. Before running the first pass of each test, I rebooted the physical PC to have the clean environment.
From the tests results, you can see that NFS read times (run from VM) are quite similar to those run directly on the hardware PC.
But when it comes to 9p, the times are 4 times bigger.
The size of the test ISO is 2.7G.
The PC is running Slackware 14.2 x86_86 (kernel 4.4.17).
The VM is running Slackware 14.2 x86_86 (kernel 4.4.14).
QEMU version is 2.6.0.
QEMU is run from
qemu:///session, i.e. with regular user privileges.
On the VM, I mount the 9p in the following way:
Code:
qemu-hostfs /home/hostfs 9p trans=virtio,version=9p2000.L,cache=mmap 0 0
I tried different
cache= options, and indeed they speed up the thing.
Unfortunately, only after you have already read the data at least once.
And more importantly, syncing with host machine is not present, i.e. changing file contents on the host is not seen on the guest (it works fine with NFS).
The speed is important for me, because I'm running an interactive program from within the VM and the program has to read quite an amount of data. With
9p it's just too slow, with NFS it's just fine.
Do you have any ideas on what might be wrong with my setup, or is that just the way it is?
Thanks in advance!
BARE METAL:
First run (after reboot):
Code:
$ /usr/bin/time md5sum slackware64-14.2-install-dvd.iso
a3108044508b1b7125e359b63e611761 slackware64-14.2-install-dvd.iso
7.78user 0.92system 0:08.71elapsed 99%CPU (0avgtext+0avgdata 7504maxresident)k
5635120inputs+0outputs (1major+133minor)pagefaults 0swaps
Second run (without reboot):
Code:
$ /usr/bin/time md5sum slackware64-14.2-install-dvd.iso
a3108044508b1b7125e359b63e611761 slackware64-14.2-install-dvd.iso
7.78user 0.55system 0:08.33elapsed 100%CPU (0avgtext+0avgdata 7216maxresident)k
0inputs+0outputs (0major+136minor)pagefaults 0swaps
VM NFS (TCP):
First run (after reboot):
Code:
$ /usr/bin/time md5sum slackware64-14.2-install-dvd.iso
a3108044508b1b7125e359b63e611761 slackware64-14.2-install-dvd.iso
8.52user 1.47system 0:10.25elapsed 97%CPU (0avgtext+0avgdata 9504maxresident)k
5635112inputs+0outputs (1major+347minor)pagefaults 0swaps
Second run (without reboot):
Code:
$ /usr/bin/time md5sum slackware64-14.2-install-dvd.iso
a3108044508b1b7125e359b63e611761 slackware64-14.2-install-dvd.iso
8.27user 1.40system 0:09.92elapsed 97%CPU (0avgtext+0avgdata 10064maxresident)k
5635048inputs+0outputs (1major+348minor)pagefaults 0swaps
VM NFS (UDP):
First run (after reboot):
Code:
$ /usr/bin/time md5sum slackware64-14.2-install-dvd.iso
a3108044508b1b7125e359b63e611761 slackware64-14.2-install-dvd.iso
7.95user 1.57system 0:10.61elapsed 89%CPU (0avgtext+0avgdata 6640maxresident)k
5635112inputs+0outputs (1major+93minor)pagefaults 0swaps
Second run (without reboot):
Code:
$ /usr/bin/time md5sum slackware64-14.2-install-dvd.iso
a3108044508b1b7125e359b63e611761 slackware64-14.2-install-dvd.iso
7.88user 1.53system 0:10.34elapsed 91%CPU (0avgtext+0avgdata 6640maxresident)k
5635048inputs+0outputs (1major+92minor)pagefaults 0swaps
VM VIRTFS (PLAN 9):
First run (after reboot):
Code:
$ /usr/bin/time md5sum slackware64-14.2-install-dvd.iso
a3108044508b1b7125e359b63e611761 slackware64-14.2-install-dvd.iso
8.37user 6.36system 0:47.76elapsed 30%CPU (0avgtext+0avgdata 6640maxresident)k
88inputs+0outputs (1major+91minor)pagefaults 0swaps
Second run (without reboot):
Code:
$ /usr/bin/time md5sum slackware64-14.2-install-dvd.iso
a3108044508b1b7125e359b63e611761 slackware64-14.2-install-dvd.iso
7.81user 6.69system 0:46.69elapsed 31%CPU (0avgtext+0avgdata 6720maxresident)k
0inputs+0outputs (0major+91minor)pagefaults 0swaps
--
Best regards,
Andrzej Telszewski
