From: "Wangyunjian(wangyunjian,TongTu)" <wangyunjian@huawei.com>
To: Stephen Hemminger <stephen@networkplumber.org>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>,
"chenbox@nvidia.com" <chenbox@nvidia.com>,
"Lilijun (Jerry)" <jerry.lilijun@huawei.com>,
"xiawei (H)" <xiawei40@huawei.com>,
wangzengyuan <wangzengyuan@huawei.com>,
"stable@dpdk.org" <stable@dpdk.org>
Subject: RE: [PATCH 1/1] vhost: fix a double fetch when dequeue offloading
Date: Mon, 23 Dec 2024 02:45:48 +0000 [thread overview]
Message-ID: <96dbb1599a3943f39c7e80d31dd3881a@huawei.com> (raw)
In-Reply-To: <20241220083546.4b5ba9c9@hermes.local>
> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Saturday, December 21, 2024 12:36 AM
> To: Wangyunjian(wangyunjian,TongTu) <wangyunjian@huawei.com>
> Cc: dev@dpdk.org; maxime.coquelin@redhat.com; chenbox@nvidia.com;
> Lilijun (Jerry) <jerry.lilijun@huawei.com>; xiawei (H) <xiawei40@huawei.com>;
> wangzengyuan <wangzengyuan@huawei.com>; stable@dpdk.org
> Subject: Re: [PATCH 1/1] vhost: fix a double fetch when dequeue offloading
>
> On Thu, 19 Dec 2024 14:38:28 +0800
> Yunjian Wang <wangyunjian@huawei.com> wrote:
>
> > diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
> > index 69901ab3b5..5c40ae7069 100644
> > --- a/lib/vhost/virtio_net.c
> > +++ b/lib/vhost/virtio_net.c
> > @@ -2914,10 +2914,12 @@ desc_to_mbuf(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
> > * in a contiguous virtual area.
> > */
> > copy_vnet_hdr_from_desc(&tmp_hdr, buf_vec);
> > - hdr = &tmp_hdr;
> > } else {
> > - hdr = (struct virtio_net_hdr *)((uintptr_t)buf_vec[0].buf_addr);
> > + rte_memcpy((void *)(uintptr_t)&tmp_hdr,
> > + (void *)(uintptr_t)buf_vec[0].buf_addr,
> > + sizeof(struct virtio_net_hdr));
> > }
> > + hdr = &tmp_hdr;
>
> Since this if block is just an optimization of the case where vnet header
> is contiguous why not just always use copy_vnet_hdr_from_desc? and inline it?
I also considered using the copy_vnet_hdr_from_desc function directly.
However, in most cases, the vnet header is continuous, and reusing
copy_vnet_hdr_from_desc results in additional operations.
Thanks,
Yunjian
prev parent reply other threads:[~2024-12-23 2:45 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-19 6:38 Yunjian Wang
2024-12-19 8:24 ` David Marchand
2024-12-19 11:02 ` Wangyunjian(wangyunjian,TongTu)
2024-12-19 16:15 ` Stephen Hemminger
2024-12-20 2:17 ` Wangyunjian(wangyunjian,TongTu)
2024-12-20 4:59 ` Stephen Hemminger
2024-12-20 3:49 ` [PATCH v2 " Yunjian Wang
2024-12-20 17:10 ` Stephen Hemminger
2024-12-20 16:35 ` [PATCH " Stephen Hemminger
2024-12-23 2:45 ` Wangyunjian(wangyunjian,TongTu) [this message]
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