From: Jason Wang <jasowang@redhat.com>
To: "Liu, Yong" <yong.liu@intel.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: Thu, 11 Jul 2019 17:44:19 +0800 [thread overview]
Message-ID: <0aa6d82b-1ba1-ebcc-b7ab-80c84930e45c@redhat.com> (raw)
In-Reply-To: <86228AFD5BCD8E4EBFD2B90117B5E81E63335C49@SHSMSX103.ccr.corp.intel.com>
On 2019/7/11 下午5:37, Liu, Yong wrote:
>
>> -----Original Message-----
>> From: Jason Wang [mailto:jasowang@redhat.com]
>> Sent: Thursday, July 11, 2019 4:35 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>
>>>
>>> + len = descs[avail_idx].len;
>>> + len1 = descs[avail_idx + 1].len;
>>> + len2 = descs[avail_idx + 2].len;
>>> + len3 = descs[avail_idx + 3].len;
>>> +
>>> + if (unlikely((pkts[0]->pkt_len > (len - buf_offset)) |
>>> + (pkts[1]->pkt_len > (len1 - buf_offset)) |
>>> + (pkts[2]->pkt_len > (len2 - buf_offset)) |
>>> + (pkts[3]->pkt_len > (len3 - buf_offset))))
>>> + return -1;
>>> +
>>> + desc_addr = vhost_iova_to_vva(dev, vq,
>>> + descs[avail_idx].addr,
>>> + &len,
>>> + VHOST_ACCESS_RW);
>>> +
>>> + desc_addr1 = vhost_iova_to_vva(dev, vq,
>>> + descs[avail_idx + 1].addr,
>>> + &len1,
>>> + VHOST_ACCESS_RW);
>>> +
>>> + desc_addr2 = vhost_iova_to_vva(dev, vq,
>>> + descs[avail_idx + 2].addr,
>>> + &len2,
>>> + VHOST_ACCESS_RW);
>>> +
>>> + desc_addr3 = vhost_iova_to_vva(dev, vq,
>>> + descs[avail_idx + 3].addr,
>>> + &len3,
>>> + VHOST_ACCESS_RW);
>>
>> How can you guarantee that len3 is zero after this?
>>
> Jason,
> Here just guarantee host mapped length of desc is same as value in desc.
> If value of len matched, data can be directly copied.
>
> If anything wrong in address conversion, value of len will be mismatched.
> This case will be handled by normal path.
>
> Thanks,
> Marvin
Right, I miss-read the code.
Thanks
>
>> Thanks
next prev parent reply other threads:[~2019-07-11 9:44 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
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 [this message]
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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