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Date: Wed, 14 Aug 2019 07:53:19 -0700
From: "Jonathan Lemon" <jonathan.lemon@...il.com>
To: "Magnus Karlsson" <magnus.karlsson@...el.com>
Cc: bjorn.topel@...el.com, ast@...nel.org, daniel@...earbox.net,
netdev@...r.kernel.org, brouer@...hat.com, maximmi@...lanox.com,
bpf@...r.kernel.org, bruce.richardson@...el.com,
ciara.loftus@...el.com, jakub.kicinski@...ronome.com,
xiaolong.ye@...el.com, qi.z.zhang@...el.com,
sridhar.samudrala@...el.com, kevin.laatz@...el.com,
ilias.apalodimas@...aro.org, kiran.patil@...el.com,
axboe@...nel.dk, maciej.fijalkowski@...el.com,
maciejromanfijalkowski@...il.com, intel-wired-lan@...ts.osuosl.org
Subject: Re: [PATCH bpf-next v4 6/8] samples/bpf: add use of need_wakeup flag
in xdpsock
On 14 Aug 2019, at 0:27, Magnus Karlsson wrote:
> This commit adds using the need_wakeup flag to the xdpsock sample
> application. It is turned on by default as we think it is a feature
> that seems to always produce a performance benefit, if the application
> has been written taking advantage of it. It can be turned off in the
> sample app by using the '-m' command line option.
>
> The txpush and l2fwd sub applications have also been updated to
> support poll() with multiple sockets.
>
> Signed-off-by: Magnus Karlsson <magnus.karlsson@...el.com>
Acked-by: Jonathan Lemon <jonathan.lemon@...il.com>
> ---
> samples/bpf/xdpsock_user.c | 192
> ++++++++++++++++++++++++++++-----------------
> 1 file changed, 120 insertions(+), 72 deletions(-)
>
> diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
> index 93eaaf7..da84c76 100644
> --- a/samples/bpf/xdpsock_user.c
> +++ b/samples/bpf/xdpsock_user.c
> @@ -67,8 +67,10 @@ static int opt_ifindex;
> static int opt_queue;
> static int opt_poll;
> static int opt_interval = 1;
> -static u32 opt_xdp_bind_flags;
> +static u32 opt_xdp_bind_flags = XDP_USE_NEED_WAKEUP;
> static int opt_xsk_frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE;
> +static int opt_timeout = 1000;
> +static bool opt_need_wakeup = true;
> static __u32 prog_id;
>
> struct xsk_umem_info {
> @@ -352,6 +354,7 @@ static struct option long_options[] = {
> {"zero-copy", no_argument, 0, 'z'},
> {"copy", no_argument, 0, 'c'},
> {"frame-size", required_argument, 0, 'f'},
> + {"no-need-wakeup", no_argument, 0, 'm'},
> {0, 0, 0, 0}
> };
>
> @@ -372,6 +375,7 @@ static void usage(const char *prog)
> " -z, --zero-copy Force zero-copy mode.\n"
> " -c, --copy Force copy mode.\n"
> " -f, --frame-size=n Set the frame size (must be a power of two,
> default is %d).\n"
> + " -m, --no-need-wakeup Turn off use of driver need wakeup flag.\n"
> "\n";
> fprintf(stderr, str, prog, XSK_UMEM__DEFAULT_FRAME_SIZE);
> exit(EXIT_FAILURE);
> @@ -384,8 +388,9 @@ static void parse_command_line(int argc, char
> **argv)
> opterr = 0;
>
> for (;;) {
> - c = getopt_long(argc, argv, "Frtli:q:psSNn:czf:", long_options,
> - &option_index);
> +
> + c = getopt_long(argc, argv, "Frtli:q:psSNn:czf:m",
> + long_options, &option_index);
> if (c == -1)
> break;
>
> @@ -429,6 +434,9 @@ static void parse_command_line(int argc, char
> **argv)
> break;
> case 'f':
> opt_xsk_frame_size = atoi(optarg);
> + case 'm':
> + opt_need_wakeup = false;
> + opt_xdp_bind_flags &= ~XDP_USE_NEED_WAKEUP;
> break;
> default:
> usage(basename(argv[0]));
> @@ -459,7 +467,8 @@ static void kick_tx(struct xsk_socket_info *xsk)
> exit_with_error(errno);
> }
>
> -static inline void complete_tx_l2fwd(struct xsk_socket_info *xsk)
> +static inline void complete_tx_l2fwd(struct xsk_socket_info *xsk,
> + struct pollfd *fds)
> {
> u32 idx_cq = 0, idx_fq = 0;
> unsigned int rcvd;
> @@ -468,7 +477,9 @@ static inline void complete_tx_l2fwd(struct
> xsk_socket_info *xsk)
> if (!xsk->outstanding_tx)
> return;
>
> - kick_tx(xsk);
> + if (!opt_need_wakeup || xsk_ring_prod__needs_wakeup(&xsk->tx))
> + kick_tx(xsk);
> +
> ndescs = (xsk->outstanding_tx > BATCH_SIZE) ? BATCH_SIZE :
> xsk->outstanding_tx;
>
> @@ -482,6 +493,8 @@ static inline void complete_tx_l2fwd(struct
> xsk_socket_info *xsk)
> while (ret != rcvd) {
> if (ret < 0)
> exit_with_error(-ret);
> + if (xsk_ring_prod__needs_wakeup(&xsk->umem->fq))
> + ret = poll(fds, num_socks, opt_timeout);
> ret = xsk_ring_prod__reserve(&xsk->umem->fq, rcvd,
> &idx_fq);
> }
> @@ -505,7 +518,8 @@ static inline void complete_tx_only(struct
> xsk_socket_info *xsk)
> if (!xsk->outstanding_tx)
> return;
>
> - kick_tx(xsk);
> + if (!opt_need_wakeup || xsk_ring_prod__needs_wakeup(&xsk->tx))
> + kick_tx(xsk);
>
> rcvd = xsk_ring_cons__peek(&xsk->umem->cq, BATCH_SIZE, &idx);
> if (rcvd > 0) {
> @@ -515,20 +529,25 @@ static inline void complete_tx_only(struct
> xsk_socket_info *xsk)
> }
> }
>
> -static void rx_drop(struct xsk_socket_info *xsk)
> +static void rx_drop(struct xsk_socket_info *xsk, struct pollfd *fds)
> {
> unsigned int rcvd, i;
> u32 idx_rx = 0, idx_fq = 0;
> int ret;
>
> rcvd = xsk_ring_cons__peek(&xsk->rx, BATCH_SIZE, &idx_rx);
> - if (!rcvd)
> + if (!rcvd) {
> + if (xsk_ring_prod__needs_wakeup(&xsk->umem->fq))
> + ret = poll(fds, num_socks, opt_timeout);
> return;
> + }
>
> ret = xsk_ring_prod__reserve(&xsk->umem->fq, rcvd, &idx_fq);
> while (ret != rcvd) {
> if (ret < 0)
> exit_with_error(-ret);
> + if (xsk_ring_prod__needs_wakeup(&xsk->umem->fq))
> + ret = poll(fds, num_socks, opt_timeout);
> ret = xsk_ring_prod__reserve(&xsk->umem->fq, rcvd, &idx_fq);
> }
I'll just point out that it seems a little odd that if one ring
needs a wakeup, all the rings get polled again. However, I suppose
that it does amortize costs of a kernel call.
--
Jonathan
> @@ -549,42 +568,65 @@ static void rx_drop(struct xsk_socket_info *xsk)
> static void rx_drop_all(void)
> {
> struct pollfd fds[MAX_SOCKS + 1];
> - int i, ret, timeout, nfds = 1;
> + int i, ret;
>
> memset(fds, 0, sizeof(fds));
>
> for (i = 0; i < num_socks; i++) {
> fds[i].fd = xsk_socket__fd(xsks[i]->xsk);
> fds[i].events = POLLIN;
> - timeout = 1000; /* 1sn */
> }
>
> for (;;) {
> if (opt_poll) {
> - ret = poll(fds, nfds, timeout);
> + ret = poll(fds, num_socks, opt_timeout);
> if (ret <= 0)
> continue;
> }
>
> for (i = 0; i < num_socks; i++)
> - rx_drop(xsks[i]);
> + rx_drop(xsks[i], fds);
> + }
> +}
> +
> +static void tx_only(struct xsk_socket_info *xsk, u32 frame_nb)
> +{
> + u32 idx;
> +
> + if (xsk_ring_prod__reserve(&xsk->tx, BATCH_SIZE, &idx) ==
> BATCH_SIZE) {
> + unsigned int i;
> +
> + 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;
> + xsk_ring_prod__tx_desc(&xsk->tx, idx + i)->len =
> + sizeof(pkt_data) - 1;
> + }
> +
> + xsk_ring_prod__submit(&xsk->tx, BATCH_SIZE);
> + xsk->outstanding_tx += BATCH_SIZE;
> + frame_nb += BATCH_SIZE;
> + frame_nb %= NUM_FRAMES;
> }
> +
> + complete_tx_only(xsk);
> }
>
> -static void tx_only(struct xsk_socket_info *xsk)
> +static void tx_only_all(void)
> {
> - int timeout, ret, nfds = 1;
> - struct pollfd fds[nfds + 1];
> - u32 idx, frame_nb = 0;
> + struct pollfd fds[MAX_SOCKS];
> + u32 frame_nb[MAX_SOCKS] = {};
> + int i, ret;
>
> memset(fds, 0, sizeof(fds));
> - fds[0].fd = xsk_socket__fd(xsk->xsk);
> - fds[0].events = POLLOUT;
> - timeout = 1000; /* 1sn */
> + for (i = 0; i < num_socks; i++) {
> + fds[0].fd = xsk_socket__fd(xsks[i]->xsk);
> + fds[0].events = POLLOUT;
> + }
>
> for (;;) {
> if (opt_poll) {
> - ret = poll(fds, nfds, timeout);
> + ret = poll(fds, num_socks, opt_timeout);
> if (ret <= 0)
> continue;
>
> @@ -592,69 +634,75 @@ static void tx_only(struct xsk_socket_info *xsk)
> continue;
> }
>
> - if (xsk_ring_prod__reserve(&xsk->tx, BATCH_SIZE, &idx) ==
> - BATCH_SIZE) {
> - unsigned int i;
> -
> - for (i = 0; i < BATCH_SIZE; i++) {
> - xsk_ring_prod__tx_desc(&xsk->tx, idx + i)->addr
> - = (frame_nb + i) * opt_xsk_frame_size;
> - xsk_ring_prod__tx_desc(&xsk->tx, idx + i)->len =
> - sizeof(pkt_data) - 1;
> - }
> -
> - xsk_ring_prod__submit(&xsk->tx, BATCH_SIZE);
> - xsk->outstanding_tx += BATCH_SIZE;
> - frame_nb += BATCH_SIZE;
> - frame_nb %= NUM_FRAMES;
> - }
> -
> - complete_tx_only(xsk);
> + for (i = 0; i < num_socks; i++)
> + tx_only(xsks[i], frame_nb[i]);
> }
> }
>
> -static void l2fwd(struct xsk_socket_info *xsk)
> +static void l2fwd(struct xsk_socket_info *xsk, struct pollfd *fds)
> {
> - for (;;) {
> - unsigned int rcvd, i;
> - u32 idx_rx = 0, idx_tx = 0;
> - int ret;
> + unsigned int rcvd, i;
> + u32 idx_rx = 0, idx_tx = 0;
> + int ret;
>
> - for (;;) {
> - complete_tx_l2fwd(xsk);
> + complete_tx_l2fwd(xsk, fds);
>
> - rcvd = xsk_ring_cons__peek(&xsk->rx, BATCH_SIZE,
> - &idx_rx);
> - if (rcvd > 0)
> - break;
> - }
> + rcvd = xsk_ring_cons__peek(&xsk->rx, BATCH_SIZE, &idx_rx);
> + if (!rcvd) {
> + if (xsk_ring_prod__needs_wakeup(&xsk->umem->fq))
> + ret = poll(fds, num_socks, opt_timeout);
> + return;
> + }
>
> + ret = xsk_ring_prod__reserve(&xsk->tx, rcvd, &idx_tx);
> + while (ret != rcvd) {
> + if (ret < 0)
> + exit_with_error(-ret);
> + if (xsk_ring_prod__needs_wakeup(&xsk->tx))
> + kick_tx(xsk);
> ret = xsk_ring_prod__reserve(&xsk->tx, rcvd, &idx_tx);
> - while (ret != rcvd) {
> - if (ret < 0)
> - exit_with_error(-ret);
> - ret = xsk_ring_prod__reserve(&xsk->tx, rcvd, &idx_tx);
> - }
> + }
> +
> + for (i = 0; i < rcvd; i++) {
> + u64 addr = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx)->addr;
> + u32 len = xsk_ring_cons__rx_desc(&xsk->rx, idx_rx++)->len;
> + char *pkt = xsk_umem__get_data(xsk->umem->buffer, addr);
> +
> + swap_mac_addresses(pkt);
>
> - for (i = 0; i < rcvd; i++) {
> - u64 addr = xsk_ring_cons__rx_desc(&xsk->rx,
> - idx_rx)->addr;
> - u32 len = xsk_ring_cons__rx_desc(&xsk->rx,
> - idx_rx++)->len;
> - char *pkt = xsk_umem__get_data(xsk->umem->buffer, addr);
> + hex_dump(pkt, len, addr);
> + xsk_ring_prod__tx_desc(&xsk->tx, idx_tx)->addr = addr;
> + xsk_ring_prod__tx_desc(&xsk->tx, idx_tx++)->len = len;
> + }
>
> - swap_mac_addresses(pkt);
> + xsk_ring_prod__submit(&xsk->tx, rcvd);
> + xsk_ring_cons__release(&xsk->rx, rcvd);
>
> - hex_dump(pkt, len, addr);
> - xsk_ring_prod__tx_desc(&xsk->tx, idx_tx)->addr = addr;
> - xsk_ring_prod__tx_desc(&xsk->tx, idx_tx++)->len = len;
> - }
> + xsk->rx_npkts += rcvd;
> + xsk->outstanding_tx += rcvd;
> +}
> +
> +static void l2fwd_all(void)
> +{
> + struct pollfd fds[MAX_SOCKS];
> + int i, ret;
> +
> + memset(fds, 0, sizeof(fds));
> +
> + for (i = 0; i < num_socks; i++) {
> + fds[i].fd = xsk_socket__fd(xsks[i]->xsk);
> + fds[i].events = POLLOUT | POLLIN;
> + }
>
> - xsk_ring_prod__submit(&xsk->tx, rcvd);
> - xsk_ring_cons__release(&xsk->rx, rcvd);
> + for (;;) {
> + if (opt_poll) {
> + ret = poll(fds, num_socks, opt_timeout);
> + if (ret <= 0)
> + continue;
> + }
>
> - xsk->rx_npkts += rcvd;
> - xsk->outstanding_tx += rcvd;
> + for (i = 0; i < num_socks; i++)
> + l2fwd(xsks[i], fds);
> }
> }
>
> @@ -705,9 +753,9 @@ int main(int argc, char **argv)
> if (opt_bench == BENCH_RXDROP)
> rx_drop_all();
> else if (opt_bench == BENCH_TXONLY)
> - tx_only(xsks[0]);
> + tx_only_all();
> else
> - l2fwd(xsks[0]);
> + l2fwd_all();
>
> return 0;
> }
> --
> 2.7.4
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