> Le 27 oct. 2016 ? 12:19, Wang, Zhihong <zhihong.wang at intel.com> a ?crit :
>
>
>
>> -----Original Message-----
>> From: Maxime Coquelin [mailto:maxime.coquelin at redhat.com]
>> Sent: Thursday, October 27, 2016 5:55 PM
>> To: Wang, Zhihong <zhihong.wang at intel.com>; Yuanhan Liu
>> <yuanhan.liu at linux.intel.com>; stephen at networkplumber.org; Pierre
>> Pfister (ppfister) <ppfister at cisco.com>
>> Cc: Xie, Huawei <huawei.xie at intel.com>; dev at dpdk.org;
>> vkaplans at redhat.com; mst at redhat.com
>> Subject: Re: [dpdk-dev] [PATCH v4] vhost: Add indirect descriptors support
>> to the TX path
>>
>>
>>
>> On 10/27/2016 11:10 AM, Maxime Coquelin wrote:
>>> Hi Zhihong,
>>>
>>> On 10/27/2016 11:00 AM, Wang, Zhihong wrote:
>>>> Hi Maxime,
>>>>
>>>> Seems indirect desc feature is causing serious performance
>>>> degradation on Haswell platform, about 20% drop for both
>>>> mrg=on and mrg=off (--txqflags=0xf00, non-vector version),
>>>> both iofwd and macfwd.
>>> I tested PVP (with macswap on guest) and Txonly/Rxonly on an Ivy Bridge
>>> platform, and didn't faced such a drop.
>>> Have you tried to pass indirect_desc=off to qemu cmdline to see if you
>>> recover the performance?
>>>
>>> Yuanhan, which platform did you use when you tested it with zero copy?
>>>
>>>>
>>>> I'm using RC2, and the CPU is Xeon E5-2699 v3 @ 2.30GHz.
>>>>
>>>> Could you please verify if this is true in your test?
>>> I'll try -rc1/-rc2 on my platform, and let you know.
>> As a first test, I tried again Txonly from the guest to the host (Rxonly),
>> where Tx indirect descriptors are used, on my E5-2665 @2.40GHz:
>> v16.11-rc1: 10.81Mpps
>> v16.11-rc2: 10.91Mpps
>>
>> -rc2 is even slightly better in my case.
>> Could you please run the same test on your platform?
>
> I mean to use rc2 as both host and guest, and compare the
> perf between indirect=0 and indirect=1.
>
> I use PVP traffic, tried both testpmd and OvS as the forwarding
> engine in host, and testpmd in guest.
>
> Thanks
> Zhihong
