Date: Sat, 18 Jan 2014 13:51:58 -0500 From: Eric Dombroski <eric@edombroski.com> To: freebsd-stable@freebsd.org Subject: Major performance/stability regression in virtio network drivers between 9.2-RELEASE and 10.0-RC5 Message-ID: <CA%2B=CMd3jeNevdzMQTCG5hEE91Tnmy=9VKfSOdsJaiqo7jYTvJg@mail.gmail.com>
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Hello:
I believe there is a major performance regression between FreeBSD
9.2-RELEASE and 10.0-RC5 involving the virtio network drivers (vtnet) and
handling incoming traffic. Below are the results of some iperf tests and
large dd operations over NFS. Write throughput goes from ~40Gbps to
~2.4Gbps from 9.2 to 10.0RC5, and over time the connection becomes unstable
("no buffer space available"), requiring the interface to be taken down/up.
These results are on fresh installs of 9.2 and 10.0RC5, no sysctl tweaks on
either system.
I can't reproduce this using an Intel 1Gbps ethernet through PCIe
passthrough, although I suspect the problem manifests itself over 1Gbps
speeds anyway.
Tests:
Client (host):
root@gogo:~# uname -a
Linux gogo 3.2.0-4-amd64 #1 SMP Debian 3.2.51-1 x86_64 GNU/Linux
root@gogo:~# kvm -version
QEMU emulator version 1.1.2 (qemu-kvm-1.1.2+dfsg-6, Debian), Copyright
(c) 2003-2008 Fabrice Bellard
root@gogo:~# lsmod | grep vhost
vhost_net 27436 3
tun 18337 8 vhost_net
macvtap 17633 1 vhost_net
Command: iperf -c 192.168.100.x -t 60
Server (FreeBSD 9.2 VM):
root@umarotest:~ # uname -a
FreeBSD umarotest 9.2-RELEASE-p3 FreeBSD 9.2-RELEASE-p3 #0: Sat Jan
11 03:25:02 UTC 2014
root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC
amd64
root@umarotest:~ # iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 64.0 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.100.44 port 5001 connected with 192.168.100.1
port 58996
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-60.0 sec 293 GBytes 41.9 Gbits/sec
[ 5] local 192.168.100.44 port 5001 connected with 192.168.100.1
port 58997
[ 5] 0.0-60.0 sec 297 GBytes 42.5 Gbits/sec
[ 4] local 192.168.100.44 port 5001 connected with 192.168.100.1
port 58998
[ 4] 0.0-60.0 sec 291 GBytes 41.6 Gbits/sec
[ 5] local 192.168.100.44 port 5001 connected with 192.168.100.1
port 58999
[ 5] 0.0-60.0 sec 297 GBytes 42.6 Gbits/sec
[ 4] local 192.168.100.44 port 5001 connected with 192.168.100.1
port 59000
[ 4] 0.0-60.0 sec 297 GBytes 42.5 Gbits/sec
While pinging out from the server to the client, I do not get any
errors.
root@umaro:~ # uname -a FreeBSD umaro 10.0-RC5 FreeBSD 10.0-RC5 #0
r260430: Wed Jan 8 05:10:04 UTC 2014
root@snap.freebsd.org:/usr/obj/usr/src/sys/GENERIC
amd64
root@umaro:~ # iperf -s
------------------------------------------------------------
Server listening on TCP port 5001
TCP window size: 64.0 KByte (default)
------------------------------------------------------------
[ 4] local 192.168.100.5 port 5001 connected with 192.168.100.1 port
50264
[ ID] Interval Transfer Bandwidth
[ 4] 0.0-60.0 sec 16.7 GBytes 2.39 Gbits/sec
[ 5] local 192.168.100.5 port 5001 connected with 192.168.100.1 port
50265
[ 5] 0.0-60.0 sec 18.3 GBytes 2.62 Gbits/sec
[ 4] local 192.168.100.5 port 5001 connected with 192.168.100.1 port
50266
[ 4] 0.0-60.0 sec 16.8 GBytes 2.40 Gbits/sec
[ 5] local 192.168.100.5 port 5001 connected with 192.168.100.1 port
50267
[ 5] 0.0-60.0 sec 16.8 GBytes 2.40 Gbits/sec
[ 4] local 192.168.100.5 port 5001 connected with 192.168.100.1 port
50268
[ 4] 0.0-60.0 sec 16.8 GBytes 2.41 Gbits/sec
*** While pinging out from the server to client, frequent "ping:
sendto: No space left on device" errors ***
After a while, I can also reliably re-produce more egregious "ping:
sendto: No buffer space available" errors after doing a large sequential
write over NFS:
mount -t nfs -o rsize=65536,wsize=65536 192.168.100.5:/storage/shared
/mnt/nfs
dd if=/dev/zero of=/mnt/nfs/testfile bs=1M count=30000
I am going to file a freebsd bug report as well.
Thanks,
Eric
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