Lines Matching +full:mode +full:- +full:flag
1 .. SPDX-License-Identifier: GPL-2.0
20 XDP programs to redirect frames to a memory buffer in a user-space
59 corresponding two rings, sets the XDP_SHARED_UMEM flag in the bind
64 single-consumer / single-producer (for performance reasons), the new
72 user-space application can place an XSK at an arbitrary place in this
83 when loading the XDP program, XDP_SKB mode is employed that uses SKBs
85 space. A fallback mode that works for any network device. On the other
99 http://vger.kernel.org/lpc_net2018_talks/lpc18_paper_af_xdp_perf-v2.pdf. Do
106 ----
109 equal-sized frames. An UMEM is associated to a netdev and a specific
117 the next socket B can do this by setting the XDP_SHARED_UMEM flag in
121 The UMEM has two single-producer/single-consumer rings that are used
123 user-space application.
126 -----
129 TX. All rings are single-producer/single-consumer, so the user-space
145 calls and mmapped to user-space using the appropriate offset to mmap()
155 user-space to kernel-space. The UMEM addrs are passed in the ring. As
162 running the application with aligned chunk mode, the kernel will mask
166 chunks mode, then the incoming addr will be left untouched.
173 kernel-space to user-space. Just like the FILL ring, UMEM indices are
176 Frames passed from the kernel to user-space are frames that has been
177 sent (TX ring) and can be used by user-space again.
247 ------------------------------------
249 When you bind to a socket, the kernel will first try to use zero-copy
250 copy. If zero-copy is not supported, it will fall back on using copy
251 mode, i.e. copying all packets out to user space. But if you would
252 like to force a certain mode, you can use the following flags. If you
253 pass the XDP_COPY flag to the bind call, the kernel will force the
254 socket into copy mode. If it cannot use copy mode, the bind call will
255 fail with an error. Conversely, the XDP_ZEROCOPY flag will force the
256 socket into zero-copy mode or fail.
258 XDP_SHARED_UMEM bind flag
259 -------------------------
261 This flag enables you to bind multiple sockets to the same UMEM. It
263 netdevs/devices. In this mode, each socket has their own RX and TX
272 we have bound to. To use this mode, create the first socket and bind
283 round-robin example of distributing packets is shown below:
285 .. code-block:: c
303 rr = (rr + 1) & (MAX_SOCKS - 1);
314 Libbpf uses this mode if you create more than one socket tied to the
350 XDP_USE_NEED_WAKEUP bind flag
351 -----------------------------
353 This option adds support for a new flag called need_wakeup that is
356 need_wakeup flag will be set if the kernel needs to be explicitly
357 woken up by a syscall to continue processing packets. If the flag is
360 If the flag is set on the FILL ring, the application needs to call
366 need_wakeup flag is set so that user space can put buffers on the
370 If the flag is set for the TX ring, it means that the application
375 An example of how to use this flag can be found in
379 .. code-block:: c
384 I.e., only use the syscall if the flag is set.
386 We recommend that you always enable this mode as it usually leads to
393 ------------------------------------------------------
402 socket. But if the XDP_SHARED_UMEM flag is used, any socket after the
405 be used. Note, that the rings are single-producer single-consumer, so
409 In libbpf, you can create Rx-only and Tx-only sockets by supplying
413 If you create a Tx-only socket, we recommend that you do not put any
419 -----------------------
434 be dealt with in separate sections for each UMEM flag.
437 -------------------------
442 .. code-block:: c
451 ----------------------
454 XDP_OPTIONS_ZEROCOPY which tells you if zero-copy is on or not.
460 user-space application and the XDP program. For a complete setup and
461 usage example, please refer to the sample application. The user-space
466 .. code-block:: c
470 int index = ctx->rx_queue_index;
483 .. code-block:: c
505 __u32 entries = *ring->producer - *ring->consumer;
508 return -1;
510 // read-barrier!
512 *item = ring->desc[*ring->consumer & (RING_SIZE - 1)];
513 (*ring->consumer)++;
519 u32 free_entries = RING_SIZE - (*ring->producer - *ring->consumer);
522 return -1;
524 ring->desc[*ring->producer & (RING_SIZE - 1)] = *item;
526 // write-barrier!
528 (*ring->producer)++;
543 ethtool -N p3p2 rx-flow-hash udp4 fn
544 ethtool -N p3p2 flow-type udp4 src-port 4242 dst-port 4242 \
547 Running the rxdrop benchmark in XDP_DRV mode can then be done
550 samples/bpf/xdpsock -i p3p2 -q 16 -r -N
552 For XDP_SKB mode, use the switch "-S" instead of "-N" and all options
553 can be displayed with "-h", as usual.
581 sudo ethtool -L <interface> combined 1
588 sudo ethtool -N <interface> rx-flow-hash udp4 fn
589 sudo ethtool -N <interface> flow-type udp4 src-port 4242 dst-port \
596 in copy mode?
603 to the same queue id Y. In zero-copy mode, you should use the
616 XDP_SHARED_UMEM flag.
621 - Björn Töpel (AF_XDP core)
622 - Magnus Karlsson (AF_XDP core)
623 - Alexander Duyck
624 - Alexei Starovoitov
625 - Daniel Borkmann
626 - Jesper Dangaard Brouer
627 - John Fastabend
628 - Jonathan Corbet (LWN coverage)
629 - Michael S. Tsirkin
630 - Qi Z Zhang
631 - Willem de Bruijn