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From: "Liu, Yong" <yong.liu@intel.com>
To: Jason Wang <jasowang@redhat.com>,
	"Bie, Tiwei" <tiwei.bie@intel.com>,
	"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>,
	"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [RFC PATCH 02/13] add vhost packed ring fast enqueue function
Date: Wed, 10 Jul 2019 07:30:15 +0000	[thread overview]
Message-ID: <86228AFD5BCD8E4EBFD2B90117B5E81E63334CE6@SHSMSX103.ccr.corp.intel.com> (raw)
In-Reply-To: <daff52b2-9092-d9ab-83b4-1ca2f3003eec@redhat.com>



> -----Original Message-----
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Wednesday, July 10, 2019 12:28 PM
> To: Liu, Yong <yong.liu@intel.com>; Bie, Tiwei <tiwei.bie@intel.com>;
> maxime.coquelin@redhat.com; dev@dpdk.org
> Subject: Re: [dpdk-dev] [RFC PATCH 02/13] add vhost packed ring fast enqueue
> function
> 
> 
> On 2019/7/9 上午1:13, Marvin Liu wrote:
> > In fast enqueue function, will first check whether descriptors are
> > cache aligned. Fast enqueue function will check prerequisites in the
> > beginning. Fast enqueue function do not support chained mbufs, normal
> > function will handle that.
> >
> > Signed-off-by: Marvin Liu <yong.liu@intel.com>
> 
> Any reason for not letting compiler to unroll the loops?
> 

Hi Jason,
I'm not sure about how much compiler can help on unrolling loops as it can't know how much loops will create in one call.
After force not using unroll-loop optimization by "-fno-unroll-loops", virtio_dev_rx_packed function size remained the same.
So look like gcc unroll-loop optimization do not help here. 

And fast enqueue function not only did unroll loop, it also checked cache alignment which can help performance in another side.

Regards,
Marvin

> Thanks
> 


  reply	other threads:[~2019-07-10  7:30 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-08 17:13 [dpdk-dev] [RFC] vhost packed ring performance optimization Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 01/13] add vhost normal enqueue function Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 02/13] add vhost packed ring fast " Marvin Liu
     [not found]   ` <CGME20190708113801eucas1p25d89717d8b298790326077852c9933c8@eucas1p2.samsung.com>
2019-07-08 11:37     ` Ilya Maximets
2019-07-09  1:15       ` Liu, Yong
2019-07-10  4:28   ` Jason Wang
2019-07-10  7:30     ` Liu, Yong [this message]
2019-07-11  4:11       ` Jason Wang
2019-07-11  9:49         ` Liu, Yong
2019-07-11  9:54           ` Jason Wang
2019-08-13  9:02             ` Liu, Yong
2019-07-11  8:35   ` Jason Wang
2019-07-11  9:37     ` Liu, Yong
2019-07-11  9:44       ` Jason Wang
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 03/13] add vhost packed ring normal dequeue function Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 04/13] add vhost packed ring fast " Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 05/13] add enqueue shadow used descs update and flush functions Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 06/13] add vhost fast enqueue flush function Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 07/13] add vhost dequeue shadow descs update function Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 08/13] add vhost fast dequeue flush function Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 09/13] replace vhost enqueue packed ring function Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 10/13] add vhost fast zero copy dequeue " Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 11/13] replace vhost " Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 12/13] support inorder in vhost dequeue path Marvin Liu
2019-07-08 17:13 ` [dpdk-dev] [RFC PATCH 13/13] remove useless vhost functions Marvin Liu

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