On Tue, Jan 19, 2021 at 06:53:29PM +0800, Xuan Zhuo wrote: > On Tue, 19 Jan 2021 04:50:30 -0500, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > On Tue, Jan 19, 2021 at 05:45:09PM +0800, Xuan Zhuo wrote: > > > v2: > > > 1. add priv_flags IFF_TX_SKB_NO_LINEAR instead of netdev_feature > > > 2. split the patch to three: > > > a. add priv_flags IFF_TX_SKB_NO_LINEAR > > > b. virtio net add priv_flags IFF_TX_SKB_NO_LINEAR > > > c. When there is support this flag, construct skb without linear space > > > 3. use ERR_PTR() and PTR_ERR() to handle the err > > > > > > > > > v1 message log: > > > --------------- > > > > > > This patch is used to construct skb based on page to save memory copy > > > overhead. > > > > > > This has one problem: > > > > > > We construct the skb by fill the data page as a frag into the skb. In > > > this way, the linear space is empty, and the header information is also > > > in the frag, not in the linear space, which is not allowed for some > > > network cards. For example, Mellanox Technologies MT27710 Family > > > [ConnectX-4 Lx] will get the following error message: > > > > > > mlx5_core 0000:3b:00.1 eth1: Error cqe on cqn 0x817, ci 0x8, qn 0x1dbb, opcode 0xd, syndrome 0x1, vendor syndrome 0x68 > > > 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > 00000030: 00 00 00 00 60 10 68 01 0a 00 1d bb 00 0f 9f d2 > > > WQE DUMP: WQ size 1024 WQ cur size 0, WQE index 0xf, len: 64 > > > 00000000: 00 00 0f 0a 00 1d bb 03 00 00 00 08 00 00 00 00 > > > 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > 00000020: 00 00 00 2b 00 08 00 00 00 00 00 05 9e e3 08 00 > > > 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > > mlx5_core 0000:3b:00.1 eth1: ERR CQE on SQ: 0x1dbb > > > > > > I also tried to use build_skb to construct skb, but because of the > > > existence of skb_shinfo, it must be behind the linear space, so this > > > method is not working. We can't put skb_shinfo on desc->addr, it will be > > > exposed to users, this is not safe. > > > > > > Finally, I added a feature NETIF_F_SKB_NO_LINEAR to identify whether the > > > network card supports the header information of the packet in the frag > > > and not in the linear space. > > > > > > ---------------- Performance Testing ------------ > > > > > > The test environment is Aliyun ECS server. > > > Test cmd: > > > ``` > > > xdpsock -i eth0 -t -S -s <msg size> > > > ``` > > > > > > Test result data: > > > > > > size 64 512 1024 1500 > > > copy 1916747 1775988 1600203 1440054 > > > page 1974058 1953655 1945463 1904478 > > > percent 3.0% 10.0% 21.58% 32.3% > > > > Just making sure, are these test results with v2? > > The data was tested at v1, > but v2 did not modify the performance-related code. > > Thanks. Looks like v1 wouldn't even build, or did I miss anything? It would be nicer if you retested it ... > > > > > > > > > Xuan Zhuo (3): > > > net: add priv_flags for allow tx skb without linear > > > virtio-net: support IFF_TX_SKB_NO_LINEAR > > > xsk: build skb by page > > > > > > drivers/net/virtio_net.c | 3 +- > > > include/linux/netdevice.h | 3 ++ > > > net/xdp/xsk.c | 112 ++++++++++++++++++++++++++++++++++++++-------- > > > 3 files changed, 99 insertions(+), 19 deletions(-) > > > > > > -- > > > 1.8.3.1 > >
