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Toshiaki Makita says: ==================== This patch set introduces driver XDP for veth. Basically this is used in conjunction with redirect action of another XDP program. NIC -----------> veth===veth (XDP) (redirect) (XDP) In this case xdp_frame can be forwarded to the peer veth without modification, so we can expect far better performance than generic XDP. Envisioned use-cases -------------------- * Container managed XDP program Container host redirects frames to containers by XDP redirect action, and privileged containers can deploy their own XDP programs. * XDP program cascading Two or more XDP programs can be called for each packet by redirecting xdp frames to veth. * Internal interface for an XDP bridge When using XDP redirection to create a virtual bridge, veth can be used to create an internal interface for the bridge. Implementation -------------- This changeset is making use of NAPI to implement ndo_xdp_xmit and XDP_TX/REDIRECT. This is mainly because XDP heavily relies on NAPI context. - patch 1: Export a function needed for veth XDP. - patch 2-3: Basic implementation of veth XDP. - patch 4-6: Add ndo_xdp_xmit. - patch 7-9: Add XDP_TX and XDP_REDIRECT. - patch 10: Performance optimization for multi-queue env. Tests and performance numbers ----------------------------- Tested with a simple XDP program which only redirects packets between NIC and veth. I used i40e 25G NIC (XXV710) for the physical NIC. The server has 20 of Xeon Silver 2.20 GHz cores. pktgen --(wire)--> XXV710 (i40e) <--(XDP redirect)--> veth===veth (XDP) The rightmost veth loads XDP progs and just does DROP or TX. The number of packets is measured in the XDP progs. The leftmost pktgen sends packets at 37.1 Mpps (almost 25G wire speed). veth XDP action Flows Mpps ================================ DROP 1 10.6 DROP 2 21.2 DROP 100 36.0 TX 1 5.0 TX 2 10.0 TX 100 31.0 I also measured netperf TCP_STREAM but was not so great performance due to lack of tx/rx checksum offload and TSO, etc. netperf <--(wire)--> XXV710 (i40e) <--(XDP redirect)--> veth===veth (XDP PASS) Direction Flows Gbps ============================== external->veth 1 20.8 external->veth 2 23.5 external->veth 100 23.6 veth->external 1 9.0 veth->external 2 17.8 veth->external 100 22.9 Also tested doing ifup/down or load/unload a XDP program repeatedly during processing XDP packets in order to check if enabling/disabling NAPI is working as expected, and found no problems. v8: - Don't use xdp_frame pointer address to calculate skb->head, headroom, and xdp_buff.data_hard_start. v7: - Introduce xdp_scrub_frame() to clear kernel pointers in xdp_frame and use it instead of memset(). v6: - Check skb->len only if reallocation is needed. - Add __GFP_NOWARN to alloc_page() since it can be triggered by external events. - Fix sparse warning around EXPORT_SYMBOL. v5: - Fix broken SOBs. v4: - Don't adjust MTU automatically. - Skip peer IFF_UP check on .ndo_xdp_xmit() because it is unnecessary. Add comments to explain that. - Use redirect_info instead of xdp_mem_info for storing no_direct flag to avoid per packet copy cost. v3: - Drop skb bulk xmit patch since it makes little performance difference. The hotspot in TCP skb xmit at this point is checksum computation in skb_segment and packet copy on XDP_REDIRECT due to cloned/nonlinear skb. - Fix race on closing device. - Add extack messages in ndo_bpf. v2: - Squash NAPI patch with "Add driver XDP" patch. - Remove conversion from xdp_frame to skb when NAPI is not enabled. - Introduce per-queue XDP ring (patch 8). - Introduce bulk skb xmit when XDP is enabled on the peer (patch 9). ==================== Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> |
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| certs | ||
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| drivers | ||
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| init | ||
| ipc | ||
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.