Re: [dpdk-dev] Poor Virtio PMD TX Performance

[Jason Wang <jasowang@redhat.com>]

On 06/12/2015 05:35 PM, Zhou, Tianlin wrote:
> Hi Changchun,
>
> Thanks for your response.
> Please see my embedded comments.
>
> What kind of vhost in your test? Linux vhost or dpdk user space vhost?
> [tzhou] We use Linux vhost.
>
> Do you enable the dump/log in your test? It will decrease perf of vritio.
> [tzhou] No, I did not enable dump/log in the performance testing. 
> I just opened log to debug why drop packets and then close it for higher performance.
>
>
> Which version of dpdk codes are you using? The tip codes in dpdk.org?
> [tzhou] I used DPDK 2.0.0 and l2fwd in DPDK 2.0.0.
> l2fwd start command: ./l2fwd -c 0x2 -n 1 --p 0x1
>
> qemu start command (I used the virtio interface for RX/TX in GUEST): 
> sudo kvm -m 4096M -smp 4 -hda /home/geo/yanghe/fedora20.qcow2  -boot d -daemonize -monitor \ telnet::10024,server,nowait,nodelay \ -cpu host \ -device e1000,netdev=public0,mac=00:0c:29:e1:f3:ff -netdev user,id=public0,hostfwd=tcp::11022-:22 \ -device virtio-net-pci,netdev=public1,mac=00:0c:29:e1:ff:ff,ioeventfd=on -netdev tap,id=public1,ifname=tapvm02,script=/home/geo/tzhou/kvm-image/tup.sh,downscript=no,vhost=on

To enable vhost for pmd I believe you need use vhostforce=on here.

>
> The qemu version?
> [tzhou]
> root@dw-2:/home/geo/tzhou/kvm-image# kvm -version QEMU emulator version 2.0.0 (Debian 2.0.0+dfsg-2ubuntu1.3), Copyright (c) 2003-2008 Fabrice Bellard
>
> -Tianlin
>
> -----Original Message-----
> From: Ouyang, Changchun [mailto:changchun.ouyang@intel.com]
> Sent: Monday, June 08, 2015 10:13 AM
> To: Zhou, Tianlin
> Cc: Ouyang, Changchun
> Subject: RE: Poor Virtio PMD TX Performance
>
> Hi tianlin,
>
> What kind of vhost in your test? Linux vhost or dpdk user space vhost?
>
> Do you enable the dump/log in your test? It will decrease perf of vritio.
>
> Which version of dpdk codes are you using? The tip codes in dpdk.org?
>
> The qemu version?
>
> Thanks for inputs
> Changchun
>
>
>> -----Original Message-----
>> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Zhou, Tianlin
>> Sent: Friday, June 5, 2015 5:23 PM
>> To: dev@dpdk.org
>> Subject: [dpdk-dev] Poor Virtio PMD TX Performance
>>
>> Hi there,
>>
>> We tested TX performance of Virtio PMD by DPDK l2fwd, but found even 
>> at 60KPPS (720B packet length) TX rate, there is 1/1000 packet dropping rate.
>> The log shows "No free tx descriptors to transmit" in Virtio PMD.
>> Increasing TX queues by modifying DPDK l2fwd can decreases packet 
>> dropping rate, but can't ensure no packet dropping unless 
>> retransmitting packets that can't be sent successfully.
>> Oppositely, RX rate can be 600KPPS without packet dropping.
>>
>> Test Env
>> - Host CPU: 4 cores, 2127.770MHz
>> - Host Memory: 8G
>> - Host OS: Linux dw-2 3.13.0-24-generic #46-Ubuntu SMP Thu Apr 10
>> 19:11:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
>> - Guest CPU: 4 cores, 2127.770MHz
>> - Guest Memory: 4G
>> - Guest OS: fedora20
>>
>> Anybody here face the same problem?
>>
>> -Tianlin