From: Daniel Bareiro <daniel-listas@gmx.net>
To: KVM General <kvm@vger.kernel.org>
Subject: Bandwidth in KVM VM with OpenBSD
Date: Sun, 9 Jan 2011 14:22:35 -0300 [thread overview]
Message-ID: <20110109172235.GD1757@defiant.freesoftware> (raw)
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Hi all!
I'm using an OpenBSD VM with qemu-kvm 0.12.5 (Debian repositories) and
Linux 2.6.34.5 compiled with the kernel.org sources.
I'm seeing a important difference in the bandwidth when I make a
transfer to or from a OpenBSD VM. Here are some results:
bsd:~# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 4] local 10.1.0.43 port 5001 connected with 10.1.0.65 port 55049
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 25.2 MBytes 21.1 Mbits/sec
[ 4] local 10.1.0.43 port 5001 connected with 10.1.0.65 port 55050
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 25.3 MBytes 21.2 Mbits/sec
[ 4] local 10.1.0.43 port 5001 connected with 10.1.0.65 port 55051
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 24.5 MBytes 20.5 Mbits/sec
[ 4] local 10.1.0.43 port 5001 connected with 10.1.0.65 port 55054
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 24.1 MBytes 20.2 Mbits/sec
[ 4] local 10.1.0.43 port 5001 connected with 10.1.0.65 port 55055
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 26.5 MBytes 22.2 Mbits/sec
[ 4] local 10.1.0.43 port 5001 connected with 10.1.0.65 port 55057
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.0 sec 28.9 MBytes 24.2 Mbits/sec
I also did some tests with scp, presenting a "stalled" state at various
times of the transfer:
ss01:/usr/src# scp linux-2.6.34.5.tar.bz2 viper@bsd:/tmp/
viper@bsd's password:
linux-2.6.34.5.tar.bz2 100% 65MB 1.3MB/s 00:51
Another test:
ss01:/usr/src# cat linux-2.6.34.5.tar.bz2 | nc -l -p 2222 -q 0
bsd:~# nc ss01 2222 | pv | dd of=/dev/null
64.5MB 0:00:48 [1.32MB/s] [ <=> ]
132161+1 records in
132161+1 records out
67666495 bytes transferred in 48.766 secs (1387557 bytes/sec)
Using the same test on a Debian GNU/Linux VM:
debian-test2:~# iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 85.3 KByte (default)
------------------------------------------------------------
[ 4] local 10.1.0.45 port 5001 connected with 10.1.0.65 port 42905
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-10.1 sec 111 MBytes 92.1 Mbits/sec
[ 5] local 10.1.0.45 port 5001 connected with 10.1.0.65 port 42906
[ 5] 0.0-10.0 sec 110 MBytes 92.0 Mbits/sec
[ 4] local 10.1.0.45 port 5001 connected with 10.1.0.65 port 42907
[ 4] 0.0-10.1 sec 110 MBytes 91.6 Mbits/sec
[ 5] local 10.1.0.45 port 5001 connected with 10.1.0.65 port 42908
[ 5] 0.0-10.0 sec 106 MBytes 88.4 Mbits/sec
[ 4] local 10.1.0.45 port 5001 connected with 10.1.0.65 port 42909
[ 4] 0.0-10.0 sec 109 MBytes 91.0 Mbits/sec
[ 5] local 10.1.0.45 port 5001 connected with 10.1.0.65 port 42910
[ 5] 0.0-10.0 sec 107 MBytes 89.4 Mbits/sec
----------------------------------------------------------------------
ss01:/usr/src# scp linux-2.6.34.5.tar.bz2 root@debian-test2:/tmp/
root@debian-test2's password:
linux-2.6.34.5.tar.bz2 100% 65MB 12.9MB/s 00:05
----------------------------------------------------------------------
ss01:/usr/src# cat linux-2.6.34.5.tar.bz2 | nc -l -p 2222 -q 0
debian-test2:~# nc ss01 2222 | pv | dd of=/dev/null
64,5MB 0:00:04 [14,9MB/s] [ <=> ]
132161+1 records in
132161+1 records out
67666495 bytes (68 MB) copied, 4,3326 s, 15,6 MB/s
In Debian virtual machines I use Virtio (disk only). But this
substantial difference may be due to the use of Virtio or another
reason? The network interface I'm using OpenBSD is a e1000. The network
interface used in Debian virtual machine is a Realtek.
Thanks in advance for your reply.
Regards,
Daniel
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