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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Cc: "Wang, Zhihong" <zhihong.wang@intel.com>,
	"stephen@networkplumber.org" <stephen@networkplumber.org>,
	"Pierre Pfister (ppfister)" <ppfister@cisco.com>,
	"Xie, Huawei" <huawei.xie@intel.com>,
	"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: Fri, 4 Nov 2016 12:39:59 +0100	[thread overview]
Message-ID: <961a0207-8a78-faf1-480b-5f09d19575c5@redhat.com> (raw)
In-Reply-To: <20161104113628.GC16751@yliu-dev.sh.intel.com>



On 11/04/2016 12:36 PM, Yuanhan Liu wrote:
> On Fri, Nov 04, 2016 at 12:22:47PM +0100, Maxime Coquelin wrote:
>>
>>
>>>>>> Hi Maxime,
>>>>>>
>>>>>> I did a little more macswap test and found out more stuff here:
>>>>> Thanks for doing more tests.
>>>>>
>>>>>>
>>>>>> 1. I did loopback test on another HSW machine with the same H/W,
>>>>>>    and indirect_desc on and off seems have close perf
>>>>>>
>>>>>> 2. So I checked the gcc version:
>>>>>>
>>>>>>     *  Previous: gcc version 6.2.1 20160916 (Fedora 24)
>>>>>>
>>>>>>     *  New: gcc version 5.4.0 20160609 (Ubuntu 16.04.1 LTS)
>>>>>
>>>>> On my side, I tested with RHEL7.3:
>>>>> - gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-11)
>>>>>
>>>>> It certainly contains some backports from newer GCC versions.
>>>>>
>>>>>>
>>>>>>    On previous one indirect_desc has 20% drop
>>>>>>
>>>>>> 3. Then I compiled binary on Ubuntu and scp to Fedora, and as
>>>>>>    expected I got the same perf as on Ubuntu, and the perf gap
>>>>>>    disappeared, so gcc is definitely one factor here
>>>>>>
>>>>>> 4. Then I use the Ubuntu binary on Fedora for PVP test, then the
>>>>>>    perf gap comes back again and the same with the Fedora binary
>>>>>>    results, indirect_desc causes about 20% drop
>>>>>
>>>>> Let me know if I understand correctly:
>>>
>>> Yes, and it's hard to breakdown further at this time.
>>>
>>> Also we may need to check whether it's caused by certain NIC
>>> model. Unfortunately I don't have the right setup right now.
>>>
>>>>> Loopback test with macswap:
>>>>> - gcc version 6.2.1 : 20% perf drop
>>>>> - gcc version 5.4.0 : No drop
>>>>>
>>>>> PVP test with macswap:
>>>>> - gcc version 6.2.1 : 20% perf drop
>>>>> - gcc version 5.4.0 : 20% perf drop
>>>>
>>>> I forgot to ask, did you recompile only host, or both host and guest
>>>> testmpd's in your test?
>>
>>> Both.
>>
>> I recompiled testpmd on a Fedora 24 machine using GCC6:
>
> Have you built host DPDK with gcc6 as well?

Yes, I use the same build based on GCC6 on both sides.

>
> 	--yliu
>
>> gcc (GCC) 6.1.1 20160621 (Red Hat 6.1.1-3)
>> Testing loopback with macswap on my Haswell RHEL7.3 machine gives me the
>> following results:
>>  - indirect on: 7.75Mpps
>>  - indirect off: 7.35Mpps
>>
>> Surprisingly, I get better results with indirect on my setup (I
>> reproduced the tests multiple times).
>>
>> Do you have a document explaining the tuning/config you apply to both the
>> host and the guest (isolation, HT, hugepage size, ...) in your
>> setup?
>>
>> Regards,
>> Maxime

  reply	other threads:[~2016-11-04 11:40 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
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 [this message]
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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