Re: [dpdk-dev] [PATCH v6 06/10] eal: register non-EAL threads as lcores

[Thomas Monjalon <thomas@monjalon.net>]

03/11/2022 10:02, Morten Brørup:
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of David Marchand
> > Sent: Monday, 6 July 2020 22.53
> > 
> > DPDK allows calling some part of its API from a non-EAL thread but this
> > has some limitations.
> > OVS (and other applications) has its own thread management but still
> > want to avoid such limitations by hacking RTE_PER_LCORE(_lcore_id) and
> > faking EAL threads potentially unknown of some DPDK component.
> > 
> > Introduce a new API to register non-EAL thread and associate them to a
> > free lcore with a new NON_EAL role.
> > This role denotes lcores that do not run DPDK mainloop and as such
> > prevents use of rte_eal_wait_lcore() and consorts.
> > 
> > Multiprocess is not supported as the need for cohabitation with this
> > new
> > feature is unclear at the moment.
> > 
> > Signed-off-by: David Marchand <david.marchand@redhat.com>
> > Acked-by: Andrew Rybchenko <arybchenko@solarflare.com>
> > Acked-by: Thomas Monjalon <thomas@monjalon.net>
> > ---
> 
> Following up on a two+ years old patch series, triggered by the discussion [1] about statistics counters in the mempool library...
> 
> The rte_lcore_role_t enum values are missing the RTE_ prefix, and the meanings of the four values should be documented with comments in the source code.
> 
> Also, the documentation [2] could benefit from some elaboration about the lcore roles. I had to read the source code in depth to understand that each "registered non-EAL thread" has a unique lcore_id, which is not used by any other EAL or non-EAL thread.

You probably have the best point of view to improve the documentation.
Feel free to work on a patch.

> [1]: http://inbox.dpdk.org/dev/98CBD80474FA8B44BF855DF32C47DC35D8747D@smartserver.smartshare.dk/T/#u
> [2]: http://doc.dpdk.org/guides/prog_guide/env_abstraction_layer.html#multiple-pthread