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From: Jason Wang <jasowang@redhat.com>
To: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: virtualization <virtualization@lists.linux-foundation.org>,
	"Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH 2/6] virtio: split: alloc indirect desc with extra
Date: Mon, 10 Jan 2022 15:41:27 +0800	[thread overview]
Message-ID: <CACGkMEsV-GLLUmTnBHBUou_2+urkpaV4A54cD8wwoH-6eoer=w@mail.gmail.com> (raw)
In-Reply-To: <1641799153.8704977-1-xuanzhuo@linux.alibaba.com>

On Mon, Jan 10, 2022 at 3:24 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
>
> On Mon, 10 Jan 2022 14:43:39 +0800, Jason Wang <jasowang@redhat.com> wrote:
> >
> > 在 2022/1/7 下午2:33, Xuan Zhuo 写道:
> > > In the scenario where indirect is not used, each desc corresponds to an
> > > extra, which is used to record information such as dma, flags, and
> > > next.
> > >
> > > In the scenario of using indirect, the assigned desc does not have the
> > > corresponding extra record dma information, and the dma information must
> > > be obtained from the desc when unmap.
> > >
> > > This patch allocates the corresponding extra array when indirect desc is
> > > allocated. This has these advantages:
> > > 1. Record the dma information of desc, no need to read desc when unmap
> > > 2. It will be more convenient and unified in processing
> > > 3. Some additional information can be recorded in extra, which will be
> > >     used in subsequent patches.
> >
> >
> > Two questions:
> >
> > 1) Is there any performance number for this change? I guess it gives
> > more stress on the cache.
>
> I will add performance test data in the next version.
>
> > 2) Is there a requirement to mix the pre mapped sg with unmapped sg? If
> > not, a per virtqueue flag looks sufficient
>
> There is this requirement. For example, in the case of AF_XDP, a patcket
> contains two parts, one is virtio_net_hdr, and the other is the actual data
> packet from AF_XDP. The former is unmapped sg, and the latter is pre mapped sg.

Any chance to map virtio_net_hdr() manually by AF_XDP routine in this case?

Thanks

>
> Thanks.
>
> >
> > Thanks
> >
> >
>

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  reply	other threads:[~2022-01-10  7:41 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-07  6:33 [PATCH 0/6] virtio: support advance DMA Xuan Zhuo
2022-01-07  6:33 ` [PATCH 1/6] virtio: rename vring_unmap_state_packed() to vring_unmap_extra_packed() Xuan Zhuo
2022-01-10  6:19   ` Jason Wang
2022-01-07  6:33 ` [PATCH 2/6] virtio: split: alloc indirect desc with extra Xuan Zhuo
2022-01-10  6:43   ` Jason Wang
2022-01-10  7:19     ` Xuan Zhuo
2022-01-10  7:41       ` Jason Wang [this message]
2022-01-10  7:52         ` Xuan Zhuo
2022-01-10  8:54           ` Jason Wang
2022-01-10  9:23             ` Xuan Zhuo
2022-01-10  9:49               ` Michael S. Tsirkin
2022-01-10  9:58                 ` Xuan Zhuo
2022-01-10 10:06                   ` Michael S. Tsirkin
2022-01-11  2:44               ` Jason Wang
2022-01-11  5:57                 ` Xuan Zhuo
2022-01-07  6:33 ` [PATCH 3/6] virtio: packed: " Xuan Zhuo
2022-01-07  6:33 ` [PATCH 4/6] virtio: split: virtqueue_add_split() support dma address Xuan Zhuo
2022-01-10  6:45   ` Jason Wang
2022-01-10  7:24     ` Xuan Zhuo
2022-01-07  6:33 ` [PATCH 5/6] virtio: packed: virtqueue_add_packed() " Xuan Zhuo
2022-01-07  6:33 ` [PATCH 6/6] virtio: add api virtio_dma_map() for advance dma Xuan Zhuo
2022-01-10  7:12   ` Michael S. Tsirkin
2022-01-10  7:24     ` Xuan Zhuo
2022-01-10  9:59 ` [PATCH 0/6] virtio: support advance DMA Michael S. Tsirkin
2022-01-11  2:54   ` Jason Wang
2022-01-11  6:17     ` Xuan Zhuo

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