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

[Morten Brørup]

> From: dev [mailto:dev-bounces at 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 at redhat.com>
> Acked-by: Andrew Rybchenko <arybchenko at solarflare.com>
> Acked-by: Thomas Monjalon <thomas at 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.

[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