[dpdk-dev] [PATCH v3 0/5] vhost: optimize enqueue

[Jianbo Liu]

On 22 September 2016 at 14:58, Wang, Zhihong <zhihong.wang at intel.com> wrote:
>
>
>> -----Original Message-----
>> From: Jianbo Liu [mailto:jianbo.liu at linaro.org]
>> Sent: Thursday, September 22, 2016 1:48 PM
>> To: Yuanhan Liu <yuanhan.liu at linux.intel.com>
>> Cc: Wang, Zhihong <zhihong.wang at intel.com>; Maxime Coquelin
>> <maxime.coquelin at redhat.com>; dev at dpdk.org
>> Subject: Re: [dpdk-dev] [PATCH v3 0/5] vhost: optimize enqueue
>>
>> On 22 September 2016 at 10:29, Yuanhan Liu <yuanhan.liu at linux.intel.com>
>> wrote:
>> > On Wed, Sep 21, 2016 at 08:54:11PM +0800, Jianbo Liu wrote:
>> >> >> > My setup consists of one host running a guest.
>> >> >> > The guest generates as much 64bytes packets as possible using
>> >> >>
>> >> >> Have you tested with other different packet size?
>> >> >> My testing shows that performance is dropping when packet size is
>> more
>> >> >> than 256.
>> >> >
>> >> >
>> >> > Hi Jianbo,
>> >> >
>> >> > Thanks for reporting this.
>> >> >
>> >> >  1. Are you running the vector frontend with mrg_rxbuf=off?
>> >> >
>> Yes, my testing is mrg_rxbuf=off, but not vector frontend PMD.
>>
>> >> >  2. Could you please specify what CPU you're running? Is it Haswell
>> >> >     or Ivy Bridge?
>> >> >
>> It's an ARM server.
>>
>> >> >  3. How many percentage of drop are you seeing?
>> The testing result:
>> size (bytes)     improvement (%)
>> 64                   3.92
>> 128                 11.51
>> 256                  24.16
>> 512                  -13.79
>> 1024                -22.51
>> 1500                -12.22
>> A correction is that performance is dropping if byte size is larger than 512.
>
>
> Jianbo,
>
> Could you please verify does this patch really cause enqueue perf to drop?
>
> You can test the enqueue path only by set guest to do rxonly, and compare
> the mpps by show port stats all in the guest.
>
>
Tested with testpmd, host: txonly, guest: rxonly
size (bytes)     improvement (%)
64                    4.12
128                   6
256                   2.65
512                   -1.12
1024                 -7.02