[dpdk-dev] [PATCH v3 0/5] vhost add vectorized data path

[Maxime Coquelin]

Hi Marvin,

On 10/15/20 5:28 PM, Liu, Yong wrote:
> Hi All,
> Performance gain from vectorized datapath in OVS-DPDK is around 1%, meanwhile it have a small impact of original datapath. 
> On the other hand, it will increase the complexity of vhost (new parameter introduced, prepare memory information for address translation). 
> After weighed the procs and co, I’d like to drawback this patch set.  Thanks for your time.

Thanks for running the test with the new version.
I have removed it from Patchwork.

Thanks,
Maxime

> Regards,
> Marvin
> 
>> -----Original Message-----
>> From: Maxime Coquelin <maxime.coquelin at redhat.com>
>> Sent: Monday, October 12, 2020 4:22 PM
>> To: Liu, Yong <yong.liu at intel.com>; Xia, Chenbo <chenbo.xia at intel.com>;
>> Wang, Zhihong <zhihong.wang at intel.com>
>> Cc: dev at dpdk.org
>> Subject: Re: [PATCH v3 0/5] vhost add vectorized data path
>>
>> Hi Marvin,
>>
>> On 10/9/20 10:14 AM, Marvin Liu wrote:
>>> Packed ring format is imported since virtio spec 1.1. All descriptors
>>> are compacted into one single ring when packed ring format is on. It is
>>> straight forward that ring operations can be accelerated by utilizing
>>> SIMD instructions.
>>>
>>> This patch set will introduce vectorized data path in vhost library. If
>>> vectorized option is on, operations like descs check, descs writeback,
>>> address translation will be accelerated by SIMD instructions. On skylake
>>> server, it can bring 6% performance gain in loopback case and around 4%
>>> performance gain in PvP case.
>>
>> IMHO, 4% gain on PVP is not a significant gain if we compare to the
>> added complexity. Moreover, I guess this is 4% gain with testpmd-based
>> PVP? If this is the case it may be even lower with OVS-DPDK PVP
>> benchmark, I will try to do a benchmark this week.
>>
>> Thanks,
>> Maxime
>>
>>> Vhost application can choose whether using vectorized acceleration, just
>>> like external buffer feature. If platform or ring format not support
>>> vectorized function, vhost will fallback to use default batch function.
>>> There will be no impact in current data path.
>>>
>>> v3:
>>> * rename vectorized datapath file
>>> * eliminate the impact when avx512 disabled
>>> * dynamically allocate memory regions structure
>>> * remove unlikely hint for in_order
>>>
>>> v2:
>>> * add vIOMMU support
>>> * add dequeue offloading
>>> * rebase code
>>>
>>> Marvin Liu (5):
>>>   vhost: add vectorized data path
>>>   vhost: reuse packed ring functions
>>>   vhost: prepare memory regions addresses
>>>   vhost: add packed ring vectorized dequeue
>>>   vhost: add packed ring vectorized enqueue
>>>
>>>  doc/guides/nics/vhost.rst           |   5 +
>>>  doc/guides/prog_guide/vhost_lib.rst |  12 +
>>>  drivers/net/vhost/rte_eth_vhost.c   |  17 +-
>>>  lib/librte_vhost/meson.build        |  16 ++
>>>  lib/librte_vhost/rte_vhost.h        |   1 +
>>>  lib/librte_vhost/socket.c           |   5 +
>>>  lib/librte_vhost/vhost.c            |  11 +
>>>  lib/librte_vhost/vhost.h            | 239 +++++++++++++++++++
>>>  lib/librte_vhost/vhost_user.c       |  26 +++
>>>  lib/librte_vhost/virtio_net.c       | 258 ++++-----------------
>>>  lib/librte_vhost/virtio_net_avx.c   | 344 ++++++++++++++++++++++++++++
>>>  11 files changed, 718 insertions(+), 216 deletions(-)
>>>  create mode 100644 lib/librte_vhost/virtio_net_avx.c
>>>
>