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Message-ID: <150d9a24-fbc2-0c6f-d161-2c709406b945@intel.com>
Date: Fri, 26 Apr 2019 22:27:20 +0200
From: Björn Töpel <bjorn.topel@...el.com>
To: Maxim Mikityanskiy <maximmi@...lanox.com>,
"David S. Miller" <davem@...emloft.net>,
Magnus Karlsson <magnus.karlsson@...el.com>
Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Saeed Mahameed <saeedm@...lanox.com>,
Jonathan Lemon <bsd@...com>,
Eran Ben Elisha <eranbe@...lanox.com>,
Tariq Toukan <tariqt@...lanox.com>
Subject: Re: [PATCH net-next 5/6] xsk: Change the default frame size to 4096
and allow controlling it
On 2019-04-26 13:42, Maxim Mikityanskiy wrote:
> The typical XDP memory scheme is one packet per page. Change the AF_XDP
> frame size in libbpf to 4096, which is the page size on x86, to allow
> libbpf to be used with the drivers with the packet-per-page scheme.
>
> Add a command line option -f to xdpsock to allow to specify a custom
> frame size.
>
I'd prefer size, in favor of "frame shift".
Björn
> Signed-off-by: Maxim Mikityanskiy <maximmi@...lanox.com>
> ---
> samples/bpf/xdpsock_user.c | 39 +++++++++++++++++++++++++-------------
> tools/lib/bpf/xsk.h | 2 +-
> 2 files changed, 27 insertions(+), 14 deletions(-)
>
> diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
> index a6b13025ee79..3746f699cf2f 100644
> --- a/samples/bpf/xdpsock_user.c
> +++ b/samples/bpf/xdpsock_user.c
> @@ -69,6 +69,7 @@ static int opt_queue;
> static int opt_poll;
> static int opt_interval = 1;
> static u32 opt_xdp_bind_flags;
> +static int opt_xsk_frame_shift = XSK_UMEM__DEFAULT_FRAME_SHIFT;
> static __u32 prog_id;
>
> struct xsk_umem_info {
> @@ -93,6 +94,11 @@ struct xsk_socket_info {
> static int num_socks;
> struct xsk_socket_info *xsks[MAX_SOCKS];
>
> +static inline int get_buf_size(int frames)
> +{
> + return frames << opt_xsk_frame_shift;
> +}
> +
> static unsigned long get_nsecs(void)
> {
> struct timespec ts;
> @@ -277,6 +283,12 @@ static size_t gen_eth_frame(struct xsk_umem_info *umem, u64 addr)
> static struct xsk_umem_info *xsk_configure_umem(void *buffer, u64 size)
> {
> struct xsk_umem_info *umem;
> + struct xsk_umem_config cfg = {
> + .fill_size = XSK_RING_PROD__DEFAULT_NUM_DESCS,
> + .comp_size = XSK_RING_CONS__DEFAULT_NUM_DESCS,
> + .frame_size = get_buf_size(1),
> + .frame_headroom = XSK_UMEM__DEFAULT_FRAME_HEADROOM,
> + };
> int ret;
>
> umem = calloc(1, sizeof(*umem));
> @@ -284,7 +296,7 @@ static struct xsk_umem_info *xsk_configure_umem(void *buffer, u64 size)
> exit_with_error(errno);
>
> ret = xsk_umem__create(&umem->umem, buffer, size, &umem->fq, &umem->cq,
> - NULL);
> + &cfg);
> if (ret)
> exit_with_error(-ret);
>
> @@ -325,9 +337,8 @@ static struct xsk_socket_info *xsk_configure_socket(struct xsk_umem_info *umem)
> if (ret != XSK_RING_PROD__DEFAULT_NUM_DESCS)
> exit_with_error(-ret);
> for (i = 0;
> - i < XSK_RING_PROD__DEFAULT_NUM_DESCS *
> - XSK_UMEM__DEFAULT_FRAME_SIZE;
> - i += XSK_UMEM__DEFAULT_FRAME_SIZE)
> + i < get_buf_size(XSK_RING_PROD__DEFAULT_NUM_DESCS);
> + i += get_buf_size(1))
> *xsk_ring_prod__fill_addr(&xsk->umem->fq, idx++) = i;
> xsk_ring_prod__submit(&xsk->umem->fq,
> XSK_RING_PROD__DEFAULT_NUM_DESCS);
> @@ -348,6 +359,7 @@ static struct option long_options[] = {
> {"zero-copy", no_argument, 0, 'z'},
> {"copy", no_argument, 0, 'c'},
> {"combined", no_argument, 0, 'C'},
> + {"frame-shift", required_argument, 0, 'f'},
> {0, 0, 0, 0}
> };
>
> @@ -368,8 +380,9 @@ static void usage(const char *prog)
> " -z, --zero-copy Force zero-copy mode.\n"
> " -c, --copy Force copy mode.\n"
> " -C, --combined Driver supports combined XSK and non-XSK traffic in a channel.\n"
> + " -f, --frame-shift=n Set the frame shift (default is %d, frame size is 1 << frame-shift).\n"
> "\n";
> - fprintf(stderr, str, prog);
> + fprintf(stderr, str, prog, XSK_UMEM__DEFAULT_FRAME_SHIFT);
> exit(EXIT_FAILURE);
> }
>
> @@ -380,7 +393,7 @@ static void parse_command_line(int argc, char **argv)
> opterr = 0;
>
> for (;;) {
> - c = getopt_long(argc, argv, "Frtli:q:psSNn:czC", long_options,
> + c = getopt_long(argc, argv, "Frtli:q:psSNn:czCf:", long_options,
> &option_index);
> if (c == -1)
> break;
> @@ -426,6 +439,9 @@ static void parse_command_line(int argc, char **argv)
> case 'C':
> opt_libbpf_flags |= XSK_LIBBPF_FLAGS__COMBINED_CHANNELS;
> break;
> + case 'f':
> + opt_xsk_frame_shift = atoi(optarg);
> + break;
> default:
> usage(basename(argv[0]));
> }
> @@ -589,8 +605,7 @@ static void tx_only(struct xsk_socket_info *xsk)
>
> for (i = 0; i < BATCH_SIZE; i++) {
> xsk_ring_prod__tx_desc(&xsk->tx, idx + i)->addr
> - = (frame_nb + i) <<
> - XSK_UMEM__DEFAULT_FRAME_SHIFT;
> + = get_buf_size(frame_nb + i);
> xsk_ring_prod__tx_desc(&xsk->tx, idx + i)->len =
> sizeof(pkt_data) - 1;
> }
> @@ -667,20 +682,18 @@ int main(int argc, char **argv)
> }
>
> ret = posix_memalign(&bufs, getpagesize(), /* PAGE_SIZE aligned */
> - NUM_FRAMES * XSK_UMEM__DEFAULT_FRAME_SIZE);
> + get_buf_size(NUM_FRAMES));
> if (ret)
> exit_with_error(ret);
>
> /* Create sockets... */
> - umem = xsk_configure_umem(bufs,
> - NUM_FRAMES * XSK_UMEM__DEFAULT_FRAME_SIZE);
> + umem = xsk_configure_umem(bufs, get_buf_size(NUM_FRAMES));
> xsks[num_socks++] = xsk_configure_socket(umem);
>
> if (opt_bench == BENCH_TXONLY) {
> int i;
>
> - for (i = 0; i < NUM_FRAMES * XSK_UMEM__DEFAULT_FRAME_SIZE;
> - i += XSK_UMEM__DEFAULT_FRAME_SIZE)
> + for (i = 0; i < get_buf_size(NUM_FRAMES); i += get_buf_size(1))
> (void)gen_eth_frame(umem, i);
> }
>
> diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
> index 72a49b102ab3..946245a7272e 100644
> --- a/tools/lib/bpf/xsk.h
> +++ b/tools/lib/bpf/xsk.h
> @@ -157,7 +157,7 @@ LIBBPF_API int xsk_socket__fd(const struct xsk_socket *xsk);
>
> #define XSK_RING_CONS__DEFAULT_NUM_DESCS 2048
> #define XSK_RING_PROD__DEFAULT_NUM_DESCS 2048
> -#define XSK_UMEM__DEFAULT_FRAME_SHIFT 11 /* 2048 bytes */
> +#define XSK_UMEM__DEFAULT_FRAME_SHIFT 12 /* 4096 bytes */
> #define XSK_UMEM__DEFAULT_FRAME_SIZE (1 << XSK_UMEM__DEFAULT_FRAME_SHIFT)
> #define XSK_UMEM__DEFAULT_FRAME_HEADROOM 0
>
>
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