Hi Alex,
Thanks for your reply, I will try to assign PF to VM and test.
2018-05-11 22:26 GMT+08:00 Alex Williamson <alex.williamson@xxxxxxxxxx>:
> On Fri, 11 May 2018 15:20:05 +0800
> Zhu Yijun <lovemrd@xxxxxxxxx> wrote:
>
>> Hi all,
>>
>> I booted two sr-iov guests using KVM-VFIO and pinged each other with
>> no-load one night. I found that most of the latency was little than 0.1ms,
>> but several icmp_seq greater than 10ms, even up to 1000ms;
>>
>> root@test-ping01:~# grep "time=[0-9][0-9]" outputfile
>> Mon May 7 23:05:12 201864 bytes from 192.168.0.200: icmp_seq=16703 ttl=64
>> time=123 ms
> ...
>>
>> VF used by these two guest from same port(eth0) of intel X710 Ethernet
>> controller. By contrast, I selected another two VFs and set them to
>> separate network namespace, this issue did not exits, all the latency
>> litter than 0.2ms.
>
> I think you've proved by this experiment that it's not likely to be a
> device assignment issue. Device assignment knows nothing about the
> device above the base PCI level operation, so if changing the
> networking configuration resolves the issue, the problem is perhaps
> more likely in how the PF, or maybe the guest itself, is routing VF
> packets. Thanks,
>
> Alex
