Re: [PATCH] rust: RFC/demo of safe API for Dpdk Eal, Eth and Rxq

[Gregory Etelson <getelson@nvidia.com>]

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Hello Harry,

I've been experimenting with lcore workers.
Please check out the new helloworld example:  https://github.com/getelson-at-mellanox/rdpdk/blob/safe-q/examples/helloworld.rs

There are 2 options for the example configuration:

1 Start RDPDK workers on the same cores as EAL:
    cargo run --example helloworld -- -a <PCI address> -l 0,1,3,5

2 Start RDPDK workers on dedicated cores:
    cargo run --example helloworld -- -a 0000:43:00.0 -l 0,1,3,5 -- -l 2-8

Regards,
Gregory

________________________________
From: Gregory Etelson <getelson@nvidia.com>
Sent: Sunday, April 27, 2025 21:50
To: Van Haaren, Harry <harry.van.haaren@intel.com>
Cc: Gregory Etelson <getelson@nvidia.com>; dev@dpdk.org <dev@dpdk.org>; Richardson, Bruce <bruce.richardson@intel.com>; owen.hilyard@unh.edu <owen.hilyard@unh.edu>
Subject: Re: [PATCH] rust: RFC/demo of safe API for Dpdk Eal, Eth and Rxq

Hello Harry,

> > I implemented a working echo server with your API.
> > The code is here: https://github.com/getelson-at-mellanox/rdpdk/tree/safe-q
>
> Ah cool! Great to see the API working.
>
> Reviewing the "echo.rs" code, the MbuffMempoolHandle ergonomics can perhaps be improved,
> I'll try work on that and have some API suggestions to the mailing list soon.
>
> I see the echo.rs code uses a normal "std::thread::spawn" (not DPDK lcores), there is
> some design to do here to ensuring that best practices are used;
> - any dataplane threads are registered as lcores (for best performance, mempool caches etc)
> - registered lcores are also unregistered when a thread ends (potentially allowing lcore-id reuse??)
> I haven't thought about this much, but had a brief discussion with Bruce (who is on holidays now).
>
> Suggesting that mempools & lcores are the two next up API sets to "Rustify" :)
>

I see 2 issues with the DPDK lcore API:

Unsafe "extern" lcore callback is not considered as new thread and compiler
will not run arguments Send verifications.

Also lcore arguments use generic 'void *' pointer.

Maybe Rust DPDK library needs native lcore implementation.

Differnet thread agrument types can we wrapped with a macro call.
Example is here:
https://github.com/getelson-at-mellanox/rdpdk/blob/37494bcae1fcf06bb4338519f931c2130105e576/examples/echo.rs#L88

Regards,
Gregory



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