netdev - Re: [PATCH bpf-next v2 0/7] Selftests/xsk: Test with maximum and minimum HW ring size configurations

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Message-ID: <CAJ8uoz1+ubemU4FPviGjTgtbW9f37=AxnDVXvkw85d4eQkfzhg@mail.gmail.com>
Date: Tue, 26 Mar 2024 08:23:54 +0100
From: Magnus Karlsson <magnus.karlsson@...il.com>
To: Tushar Vyavahare <tushar.vyavahare@...el.com>
Cc: bpf@...r.kernel.org, netdev@...r.kernel.org, bjorn@...nel.org, 
	magnus.karlsson@...el.com, maciej.fijalkowski@...el.com, 
	jonathan.lemon@...il.com, davem@...emloft.net, kuba@...nel.org, 
	pabeni@...hat.com, ast@...nel.org, daniel@...earbox.net, 
	tirthendu.sarkar@...el.com
Subject: Re: [PATCH bpf-next v2 0/7] Selftests/xsk: Test with maximum and
 minimum HW ring size configurations

On Thu, 21 Mar 2024 at 15:05, Tushar Vyavahare
<tushar.vyavahare@...el.com> wrote:
>
> Please find enclosed a patch set that introduces enhancements and new test
> cases to the selftests/xsk framework. These test the robustness and
> reliability of AF_XDP across both minimal and maximal ring size
> configurations.
>
> While running these tests, a bug [1] was identified when the batch size is
> roughly the same as the NIC ring size. This has now been addressed by
> Maciej's fix.
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=913eda2b08cc49d31f382579e2be34c2709eb789
>
> Patch Summary:
>
> 1. This commit syncs the ethtool.h header file between the kernel source
>    tree and the tools directory to maintain consistency.
>
> 2: Modifies the BATCH_SIZE from a constant to a variable, batch_size, to
>    support dynamic modification at runtime for testing different hardware
>    ring sizes.
>
> 3: Implements a function, get_hw_ring_size, to retrieve the current
>    maximum interface size and store this information in the
>    ethtool_ringparam structure.
>
> 4: Implements a new function, set_hw_ring_size, which allows for the
>    dynamic configuration of the ring size within an interface.
>
> 5: Introduce a new function, set_ring_size(), to manage asynchronous AF_XDP
>    socket closure. Make sure to retry the set_hw_ring_size function
>    multiple times, up to SOCK_RECONF_CTR, if it fails due to an active
>    AF_XDP socket. Immediately return an error for non-EBUSY errors.
>
> 6: Adds a new test case that puts the AF_XDP driver under stress by
>    configuring minimal hardware and software ring sizes, verifying its
>    functionality under constrained conditions.
>
> 7: Add a new test case that evaluates the maximum ring sizes for AF_XDP,
>    ensuring its reliability under maximum ring utilization.
>
> Testing Strategy:
>
> Check the system in extreme scenarios, such as maximum and minimum
> configurations. This helps identify and fix any bugs that may occur.

Thanks Tushar for this patch set. A year and a half ago, we had some
bugs in this area in the ice driver, so these new tests are very
welcome.

Acked-by: Magnus Karlsson <magnus.karlsson@...el.com>

> Tushar Vyavahare (7):
>   tools/include: copy ethtool.h to tools directory
>   selftests/xsk: make batch size variable
>   selftests/bpf: implement get_hw_ring_size function to retrieve current
>     and max interface size
>   selftests/bpf: implement set_hw_ring_size function to configure
>     interface ring size
>   selftests/xsk: introduce set_ring_size function with a retry mechanism
>     for handling AF_XDP socket closures
>   selftests/xsk: test AF_XDP functionality under minimal ring
>     configurations
>   selftests/xsk: add new test case for AF_XDP under max ring sizes
>
> Signed-off-by: Tushar Vyavahare <tushar.vyavahare@...el.com>
>
> ---
> Changelog:
> v1->v2
> - copy ethtool.h to tools directory [Stanislav]
> - Use ethtool_ringparam directly for get_hw_ring_size() [Stanislav]
> - get_hw_ring_size() and get_hw_ring_size() moved to network_helpers.c [Stanislav]
> - return -errno to match the other cases where errors are < 0. [Stanislav]
> - Cleaned up set_ring_size() function by removing unused variables and
>   refactoring logic for clarity. [Alexei]
> - Implement a retry mechanism for the set_ring_size function to handle
>   the asynchronous nature of AF_XDP socket closure. [Magnus]
> ---
>
>  tools/include/uapi/linux/ethtool.h            | 2229 ++++++++++++++++-
>  tools/testing/selftests/bpf/Makefile          |    2 +-
>  tools/testing/selftests/bpf/network_helpers.c |   48 +
>  tools/testing/selftests/bpf/network_helpers.h |    5 +
>  tools/testing/selftests/bpf/xdp_hw_metadata.c |   14 -
>  tools/testing/selftests/bpf/xskxceiver.c      |  123 +-
>  tools/testing/selftests/bpf/xskxceiver.h      |   12 +-
>  7 files changed, 2376 insertions(+), 57 deletions(-)
>
> --
> 2.34.1
>
>