Re: [PATCH net-next v3] virtio-net: page_to_skb() use build_skb when there's sufficient tailroom

[Jason Wang]

在 2021/4/27 上午10:46, Xuan Zhuo 写道:

On Tue, 20 Apr 2021 10:41:03 +0800, Jason Wang <jasow...@redhat.com> wrote:

Btw, since the patch modifies a critical path of virtio-net I suggest to
test the following cases:

1) netperf TCP stream
2) netperf UDP with packet size from 64 to PAGE_SIZE
3) XDP_PASS with 1)
4) XDP_PASS with 2)
5) XDP metadata with 1)
6) XDP metadata with 2)

I have completed the above test on the latest net-next branch. The tested script
and xdp code are as follows. The kernel is with KCOV and everything is normal
without exception.

Thanks.

Looks good.

Thanks for the testing.

## test script:
        #!/usr/bin/env sh


        for s in $(seq 64 4096)
        do
            netperf -H 192.168.122.202  -t UDP_STREAM -- -m $s
        done

        for s in $(seq 64 4096)
        do
            netperf -H 192.168.122.202  -t TCP_STREAM -- -m $s
        done

## xdp pass:

        #define KBUILD_MODNAME "foo"
        #include <linux/bpf.h>
        #include <linux/in.h>
        #include <linux/if_ether.h>
        #include <linux/if_packet.h>
        #include <linux/if_vlan.h>
        #include <linux/ip.h>
        #include <linux/icmp.h>

        #define DEFAULT_TTL 64
        #define MAX_PCKT_SIZE 600
        #define ICMP_TOOBIG_SIZE 98
        #define ICMP_TOOBIG_PAYLOAD_SIZE 92


        #define SEC(NAME) __attribute__((section(NAME), used))


        SEC("xdp")
        int _xdp(struct xdp_md *xdp)
        {
                return XDP_PASS;
        }

        char _license[] SEC("license") = "GPL";

## xdp metadata:

        #define KBUILD_MODNAME "foo"
        #include <linux/bpf.h>
        #include <linux/in.h>
        #include <linux/if_ether.h>
        #include <linux/if_packet.h>
        #include <linux/if_vlan.h>
        #include <linux/ip.h>
        #include <linux/icmp.h>

        static long (*bpf_xdp_adjust_meta)(struct xdp_md *xdp_md, int delta) = 
(void *) 54;


        #define SEC(NAME) __attribute__((section(NAME), used))

        struct meta_info {
                __u32 mark;
        } __attribute__((aligned(4)));

        SEC("xdp_mark")
        int _xdp_mark(struct xdp_md *ctx)
        {
                struct meta_info *meta;
                void *data, *data_end;
                int ret;

                /* Reserve space in-front of data pointer for our meta info.
                 * (Notice drivers not supporting data_meta will fail here!)
                 */
                ret = bpf_xdp_adjust_meta(ctx, -(int)sizeof(*meta));
                if (ret < 0)
                        return XDP_ABORTED;

                /* Notice: Kernel-side verifier requires that loading of
                 * ctx->data MUST happen _after_ helper bpf_xdp_adjust_meta(),
                 * as pkt-data pointers are invalidated.  Helpers that require
                 * this are determined/marked by bpf_helper_changes_pkt_data()
                 */
                data = (void *)(unsigned long)ctx->data;

                /* Check data_meta have room for meta_info struct */
                meta = (void *)(unsigned long)ctx->data_meta;
                if ((void *)(meta + 1) > data)
                        return XDP_ABORTED;

                meta->mark = 42;

                return XDP_PASS;
        }


        char _license[] SEC("license") = "GPL";

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