From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: "Wang, Zhihong" <zhihong.wang@intel.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 11:55:05 +0200 [thread overview]
Message-ID: <7a987be6-feec-0639-211a-462cf2b44514@redhat.com> (raw)
In-Reply-To: <a7ea1206-86ab-911c-a6b4-718e4dd5c1f2@redhat.com>
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?
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 9:55 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 [this message]
2016-10-27 10:19 ` Wang, Zhihong
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=7a987be6-feec-0639-211a-462cf2b44514@redhat.com \
--to=maxime.coquelin@redhat.com \
--cc=dev@dpdk.org \
--cc=mst@redhat.com \
--cc=ppfister@cisco.com \
--cc=stephen@networkplumber.org \
--cc=vkaplans@redhat.com \
--cc=yuanhan.liu@linux.intel.com \
--cc=zhihong.wang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).