netdev - Re: [PATCH bpf-next 0/5] selftests/xsk: xsk selftests

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Message-ID: <0fef6ce4-86cd-ae3a-0a29-953d87402afe@iogearbox.net>
Date:   Tue, 3 Nov 2020 00:08:23 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Weqaar Janjua <weqaar.janjua@...il.com>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, ast@...nel.org, magnus.karlsson@...il.com,
        bjorn.topel@...el.com
Cc:     Weqaar Janjua <weqaar.a.janjua@...el.com>, shuah@...nel.org,
        skhan@...uxfoundation.org, linux-kselftest@...r.kernel.org,
        anders.roxell@...aro.org, jonathan.lemon@...il.com,
        andrii.nakryiko@...il.com
Subject: Re: [PATCH bpf-next 0/5] selftests/xsk: xsk selftests

On 10/30/20 1:13 PM, Weqaar Janjua wrote:
> This patch set adds AF_XDP selftests based on veth to selftests/xsk/.
> 
> # Topology:
> # ---------
> #                 -----------
> #               _ | Process | _
> #              /  -----------  \
> #             /        |        \
> #            /         |         \
> #      -----------     |     -----------
> #      | Thread1 |     |     | Thread2 |
> #      -----------     |     -----------
> #           |          |          |
> #      -----------     |     -----------
> #      |  xskX   |     |     |  xskY   |
> #      -----------     |     -----------
> #           |          |          |
> #      -----------     |     ----------
> #      |  vethX  | --------- |  vethY |
> #      -----------   peer    ----------
> #           |          |          |
> #      namespaceX      |     namespaceY
> 
> These selftests test AF_XDP SKB and Native/DRV modes using veth Virtual
> Ethernet interfaces.
> 
> The test program contains two threads, each thread is single socket with
> a unique UMEM. It validates in-order packet delivery and packet content
> by sending packets to each other.
> 
> Prerequisites setup by script TEST_PREREQUISITES.sh:
> 
>     Set up veth interfaces as per the topology shown ^^:
>     * setup two veth interfaces and one namespace
>     ** veth<xxxx> in root namespace
>     ** veth<yyyy> in af_xdp<xxxx> namespace
>     ** namespace af_xdp<xxxx>
>     * create a spec file veth.spec that includes this run-time configuration
>       that is read by test scripts - filenames prefixed with TEST_XSK
>     *** xxxx and yyyy are randomly generated 4 digit numbers used to avoid
>         conflict with any existing interface.
> 
> The following tests are provided:
> 
> 1. AF_XDP SKB mode
>     Generic mode XDP is driver independent, used when the driver does
>     not have support for XDP. Works on any netdevice using sockets and
>     generic XDP path. XDP hook from netif_receive_skb().
>     a. nopoll - soft-irq processing
>     b. poll - using poll() syscall
>     c. Socket Teardown
>        Create a Tx and a Rx socket, Tx from one socket, Rx on another.
>        Destroy both sockets, then repeat multiple times. Only nopoll mode
> 	  is used
>     d. Bi-directional Sockets
>        Configure sockets as bi-directional tx/rx sockets, sets up fill
> 	  and completion rings on each socket, tx/rx in both directions.
> 	  Only nopoll mode is used
> 
> 2. AF_XDP DRV/Native mode
>     Works on any netdevice with XDP_REDIRECT support, driver dependent.
>     Processes packets before SKB allocation. Provides better performance
>     than SKB. Driver hook available just after DMA of buffer descriptor.
>     a. nopoll
>     b. poll
>     c. Socket Teardown
>     d. Bi-directional Sockets
>     * Only copy mode is supported because veth does not currently support
>       zero-copy mode
> 
> Total tests: 8.
> 
> Flow:
> * Single process spawns two threads: Tx and Rx
> * Each of these two threads attach to a veth interface within their
>    assigned namespaces
> * Each thread creates one AF_XDP socket connected to a unique umem
>    for each veth interface
> * Tx thread transmits 10k packets from veth<xxxx> to veth<yyyy>
> * Rx thread verifies if all 10k packets were received and delivered
>    in-order, and have the right content
> 
> Structure of the patch set:
> 
> Patch 1: This patch adds XSK Selftests framework under
>           tools/testing/selftests/xsk, and README
> Patch 2: Adds tests: SKB poll and nopoll mode, mac-ip-udp debug,
>           and README updates
> Patch 3: Adds tests: DRV poll and nopoll mode, and README updates
> Patch 4: Adds tests: SKB and DRV Socket Teardown, and README updates
> Patch 5: Adds tests: SKB and DRV Bi-directional Sockets, and README
>           updates
> 
> Thanks: Weqaar
> 
> Weqaar Janjua (5):
>    selftests/xsk: xsk selftests framework
>    selftests/xsk: xsk selftests - SKB POLL, NOPOLL
>    selftests/xsk: xsk selftests - DRV POLL, NOPOLL
>    selftests/xsk: xsk selftests - Socket Teardown - SKB, DRV
>    selftests/xsk: xsk selftests - Bi-directional Sockets - SKB, DRV

Thanks a lot for adding the selftests, Weqaar! Given this needs to copy quite
a bit of BPF selftest base infra e.g. from Makefiles I'd prefer if you could
place these under selftests/bpf/ instead to avoid duplicating changes into two
locations. I understand that these tests don't integrate well into test_progs,
but for example see test_tc_redirect.sh or test_tc_edt.sh for stand-alone tests
which could be done similarly with the xsk ones. Would be great if you could
integrate them and spin a v2 with that.

Thanks,
Daniel