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

[Wang, Zhihong]

> -----Original Message-----
> From: Jianbo Liu [mailto:jianbo.liu at linaro.org]
> Sent: Wednesday, September 21, 2016 4:50 PM
> To: Maxime Coquelin <maxime.coquelin at redhat.com>
> Cc: Wang, Zhihong <zhihong.wang at intel.com>; dev at dpdk.org;
> yuanhan.liu at linux.intel.com
> Subject: Re: [dpdk-dev] [PATCH v3 0/5] vhost: optimize enqueue
> 
> Hi Maxime,
> 
> On 22 August 2016 at 16:11, Maxime Coquelin
> <maxime.coquelin at redhat.com> wrote:
> > Hi Zhihong,
> >
> > On 08/19/2016 07:43 AM, Zhihong Wang wrote:
> >>
> >> This patch set optimizes the vhost enqueue function.
> >>
> ...
> 
> >
> > 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?

 2. Could you please specify what CPU you're running? Is it Haswell
    or Ivy Bridge?

 3. How many percentage of drop are you seeing?

This is expected by me because I've already found the root cause and
the way to optimize it, but since it missed the v0 deadline and
requires changes in eal/memcpy, I postpone it to the next release.

After the upcoming optimization the performance for packets larger
than 256 will be improved, and the new code will be much faster than
the current code.


Thanks
Zhihong


> 
> > pktgen-dpdk. The hosts forwards received packets back to the guest
> > using testpmd on vhost pmd interface. Guest's vCPUs are pinned to
> > physical CPUs.
> >
> > I tested it with and without your v1 patch, with and without
> > rx-mergeable feature turned ON.
> > Results are the average of 8 runs of 60 seconds:
> >
> > Rx-Mergeable ON : 7.72Mpps
> > Rx-Mergeable ON + "vhost: optimize enqueue" v1: 9.19Mpps
> > Rx-Mergeable OFF: 10.52Mpps
> > Rx-Mergeable OFF + "vhost: optimize enqueue" v1: 10.60Mpps
> >
> > Regards,
> > Maxime