Re: [dpdk-dev] 17.02 Roadmap

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

Hi Thomas,


On 10/11/2016 4:42 AM, Thomas Monjalon wrote:
> Thanks Tim for the interesting inputs.
> Some of them may require a dedicated thread to continue the discussion
> based on some preliminary specifications or drafts.
[...]
>> Interrupt Mode Support in Virtio PMD: Support for interrupt mode will be added to the virtio PMD.
> I guess you mean Rx interrupt in virtio PMD to avoid 100% polling in the VM?

Yes, it is. Previously, Stephen Hemminger has worked out a version which 
requires MSI support in uio driver, which is not upstreamed. And as 
Stephen said here 
(http://dpdk.org/ml/archives/dev/2015-December/030913.html), we will go 
with VFIO with no-IOMMU. And this dependence has been addressed in Linux 
4.8,
033291eccbd ("vfio: Include No-IOMMU mode").

Hi Stephen,

Sorry that I did not sync up with you about this topic before it's sent 
out. Have you already started the work on this topic? Or I'll work on 
this and ask your review?

>
>> Virtio-User as an Alternative Exception Path: Investigate the use of virtio-user and vhost-net as an alternative exception path to KNI that does not require out of tree drivers. This work is still at an experimental stage, so it may not be included in 17.02.
> Interesting. Please share more details of the design you are thinking of.
>
Currently, virtio-user just has the vhost-user backend (and the 
vhost-kernel path has been dropped before merge). The path of 
vhost-kernel has been dropped for bad performance comparing to 
vhost-user. And we want keep the code as simple as possible.

But after a second thought, virtio_user + vhost-kernel is a good 
candidate for exceptional path.

1. maintenance: vhost-net (kernel) is upstreamed and extensively used 
kernel module. We don't need any out-of-tree module like KNI.
2. performance: this solution would have at least similar performance 
with KNI.
3. feature: multi queue, tso, multi-seg mbuf, etc.

Any suggestions?

Thanks,
Jianfeng