Major performance/stability regression in virtio network drivers between 9.2-RELEASE and 10.0-RC5

[Eric Dombroski]

Adrian:

Yes, no change.

-Eric





On Sat, Jan 18, 2014 at 4:06 PM, Adrian Chadd <adrian.chadd at gmail.com>wrote:

> Hi,
>
> Have you tried disabling tso?
>
> Adrian
> On Jan 18, 2014 1:52 PM, "Eric Dombroski" <eric at edombroski.com> wrote:
>
>> 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 at gogo:~# uname -a
>>   Linux gogo 3.2.0-4-amd64 #1 SMP Debian 3.2.51-1 x86_64 GNU/Linux
>>   root at gogo:~# kvm -version
>>   QEMU emulator version 1.1.2 (qemu-kvm-1.1.2+dfsg-6, Debian), Copyright
>> (c) 2003-2008 Fabrice Bellard
>>   root at 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 at umarotest:~ # uname -a
>>       FreeBSD umarotest 9.2-RELEASE-p3 FreeBSD 9.2-RELEASE-p3 #0: Sat Jan
>> 11 03:25:02 UTC 2014
>> root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC
>>  amd64
>>       root at 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 at umaro:~ # uname -a FreeBSD umaro 10.0-RC5 FreeBSD 10.0-RC5 #0
>> r260430: Wed Jan  8 05:10:04 UTC 2014
>> root at snap.freebsd.org:/usr/obj/usr/src/sys/GENERIC
>>  amd64
>>       root at 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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>