Re: [PATCH v2 00/10] net/mlx5: improve MAC address and VLAN add latency

[Stephen Hemminger <stephen@networkplumber.org>]

On Tue, 22 Oct 2024 14:06:08 +0200
Dariusz Sosnowski <dsosnowski@nvidia.com> wrote:

> Whenever a new MAC address is added to the port, mlx5 PMD will:
> 
> - Add this address to `dev->data->mac_addrs[]`.
> - Destroy all control flow rules.
> - Recreate all control flow rules.
> 
> Similar logic is also implemented for VLAN filters.
> 
> Because of such logic, the latency of adding the new MAC address
> (i.e., latency of `rte_eth_dev_mac_addr_add()` function call)
> is actually linear to number of MAC addresses already configured.
> Since each operation of creating/destroying a control flow rule,
> involves an `ioctl()` syscall, on some setups the latency of adding
> a single MAC address can reach ~100ms, when port is operating with >= 100 MAC addresses.
> The same problem exists for VLAN filters (and even compounded by it).
> 
> This patchset aims to resolve these issues,
> by reworking how mlx5 PMD handles adding/removing MAC addresses and VLAN filters.
> Instead of recreating all control flow rules,
> only necessary flow rules will be created/removed on each operation,
> thus minimizing number of syscalls triggered.

Looks good.
Is there already functional test which does this? Mlx5 may not be alone
in having this problem.