From: "Wang, Zhihong" <zhihong.wang@intel.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>,
Yuanhan Liu <yuanhan.liu@linux.intel.com>,
"stephen@networkplumber.org" <stephen@networkplumber.org>,
"Pierre Pfister (ppfister)" <ppfister@cisco.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"vkaplans@redhat.com" <vkaplans@redhat.com>,
"mst@redhat.com" <mst@redhat.com>
Subject: Re: [dpdk-dev] [PATCH v4] vhost: Add indirect descriptors support to the TX path
Date: Thu, 27 Oct 2016 10:19:59 +0000 [thread overview]
Message-ID: <8F6C2BD409508844A0EFC19955BE09414E7D8C3B@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <7a987be6-feec-0639-211a-462cf2b44514@redhat.com>
> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]
> Sent: Thursday, October 27, 2016 5:55 PM
> To: Wang, Zhihong <zhihong.wang@intel.com>; Yuanhan Liu
> <yuanhan.liu@linux.intel.com>; stephen@networkplumber.org; Pierre
> Pfister (ppfister) <ppfister@cisco.com>
> Cc: Xie, Huawei <huawei.xie@intel.com>; dev@dpdk.org;
> vkaplans@redhat.com; mst@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
>
> And could you provide me more info on your fwd bench?
> Do you use dpdk-pktgen on host, or you do fwd on howt with a real NIC
> also?
>
> Thanks,
> Maxime
> > Thanks,
> > Maxime
> >
> >>
> >>
> >> Thanks
> >> Zhihong
> >>
> >>> -----Original Message-----
> >>> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]
> >>> Sent: Monday, October 17, 2016 10:15 PM
> >>> To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
> >>> Cc: Wang, Zhihong <zhihong.wang@intel.com>; Xie, Huawei
> >>> <huawei.xie@intel.com>; dev@dpdk.org; vkaplans@redhat.com;
> >>> mst@redhat.com; stephen@networkplumber.org
> >>> Subject: Re: [dpdk-dev] [PATCH v4] vhost: Add indirect descriptors
> >>> support
> >>> to the TX path
> >>>
> >>>
> >>>
> >>> On 10/17/2016 03:21 PM, Yuanhan Liu wrote:
> >>>> On Mon, Oct 17, 2016 at 01:23:23PM +0200, Maxime Coquelin wrote:
> >>>>>> On my side, I just setup 2 Windows 2016 VMs, and confirm the issue.
> >>>>>> I'll continue the investigation early next week.
> >>>>>
> >>>>> The root cause is identified.
> >>>>> When INDIRECT_DESC feature is negotiated, Windows guest uses
> indirect
> >>>>> for both Tx and Rx descriptors, whereas Linux guests (Virtio PMD &
> >>>>> virtio-net kernel driver) use indirect only for Tx.
> >>>>> I'll implement indirect support for the Rx path in vhost lib, but the
> >>>>> change will be too big for -rc release.
> >>>>> I propose in the mean time to disable INDIRECT_DESC feature in vhost
> >>>>> lib, we can still enable it locally for testing.
> >>>>>
> >>>>> Yuanhan, is it ok for you?
> >>>>
> >>>> That's okay.
> >>> I'll send a patch to disable it then.
> >>>
> >>>>
> >>>>>
> >>>>>> Has anyone already tested Windows guest with vhost-net, which
> also
> >>> has
> >>>>>> indirect descs support?
> >>>>>
> >>>>> I tested and confirm it works with vhost-net.
> >>>>
> >>>> I'm a bit confused then. IIRC, vhost-net also doesn't support indirect
> >>>> for Rx path, right?
> >>>
> >>> No, it does support it actually.
> >>> I thought it didn't support too, I misread the Kernel implementation of
> >>> vhost-net and virtio-net. Acutally, virtio-net makes use of indirect
> >>> in Rx path when mergeable buffers is disabled.
> >>>
> >>> The confusion certainly comes from me, sorry about that.
> >>>
> >>> Maxime
next prev parent reply other threads:[~2016-10-27 10:20 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-23 8:28 [dpdk-dev] [PATCH v3] " Maxime Coquelin
2016-09-23 15:49 ` Michael S. Tsirkin
2016-09-23 18:02 ` Maxime Coquelin
2016-09-23 18:06 ` Michael S. Tsirkin
2016-09-23 18:16 ` Maxime Coquelin
2016-09-23 18:22 ` Michael S. Tsirkin
2016-09-23 20:24 ` Stephen Hemminger
2016-09-26 3:03 ` Yuanhan Liu
2016-09-26 12:25 ` Michael S. Tsirkin
2016-09-26 13:04 ` Yuanhan Liu
2016-09-27 4:15 ` Yuanhan Liu
2016-09-27 7:25 ` Maxime Coquelin
2016-09-27 8:42 ` [dpdk-dev] [PATCH v4] " Maxime Coquelin
2016-09-27 12:18 ` Yuanhan Liu
2016-10-14 7:24 ` Wang, Zhihong
2016-10-14 7:34 ` Wang, Zhihong
2016-10-14 15:50 ` Maxime Coquelin
2016-10-17 11:23 ` Maxime Coquelin
2016-10-17 13:21 ` Yuanhan Liu
2016-10-17 14:14 ` Maxime Coquelin
2016-10-27 9:00 ` Wang, Zhihong
2016-10-27 9:10 ` Maxime Coquelin
2016-10-27 9:55 ` Maxime Coquelin
2016-10-27 10:19 ` Wang, Zhihong [this message]
2016-10-28 7:32 ` Pierre Pfister (ppfister)
2016-10-28 7:58 ` Maxime Coquelin
2016-11-01 8:15 ` Yuanhan Liu
2016-11-01 9:39 ` Thomas Monjalon
2016-11-02 2:44 ` Yuanhan Liu
2016-10-27 10:33 ` Yuanhan Liu
2016-10-27 10:35 ` Maxime Coquelin
2016-10-27 10:46 ` Yuanhan Liu
2016-10-28 0:49 ` Wang, Zhihong
2016-10-28 7:42 ` Maxime Coquelin
2016-10-31 10:01 ` Wang, Zhihong
2016-11-02 10:51 ` Maxime Coquelin
2016-11-03 8:11 ` Maxime Coquelin
2016-11-04 6:18 ` Xu, Qian Q
2016-11-04 7:41 ` Maxime Coquelin
2016-11-04 7:20 ` Wang, Zhihong
2016-11-04 7:57 ` Maxime Coquelin
2016-11-04 7:59 ` Maxime Coquelin
2016-11-04 10:43 ` Wang, Zhihong
2016-11-04 11:22 ` Maxime Coquelin
2016-11-04 11:36 ` Yuanhan Liu
2016-11-04 11:39 ` Maxime Coquelin
2016-11-04 12:30 ` Wang, Zhihong
2016-11-04 12:54 ` Maxime Coquelin
2016-11-04 13:09 ` Wang, Zhihong
2016-11-08 10:51 ` Wang, Zhihong
2016-10-27 10:53 ` Maxime Coquelin
2016-10-28 6:05 ` Xu, Qian Q
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