Thanks Dmitry and Bruce for your inputs. Option 1 is my favorite.
We all agree on Option 1. I will send a patch based on it.
Thank you.
> -----Original Message-----
> From: Dmitry Kozlyuk <dmitry.kozl...@gmail.com>
> Sent: Monday, 30 January 2023 12:01
> To: Ophir Munk <ophi...@nvidia.com>
> Cc: dev@dpdk.org; Ophir Munk <ophi...@mellanox.com>; Matan Azrad
> <ma...@nvidia.com>; Thomas Monjalon <ho...@monjalon.net>; Bruce
> Richardson <bruce.richard...@intel.com>; Lior Margalit
> <lmarga...@nvidia.com>
> Subject: Re: [RFC] config: customize max memzones configuration
>
> 2023-01-30 11:23 (UTC+0200), Ophir Munk:
> > In current DPDK the RTE_MAX_MEMZONE definition is unconditionally hard
> > coded as 2560. For applications requiring different values of this
> > parameter – it is more convenient to set its value as part of the
> > meson command line or to set the max value via an rte API - rather
> > than changing the dpdk source code per application.
> >
> > An example would be of an application that uses the DPDK mempool
> > library which is based on DPDK memzone library. The application may
> > need to create a number of steering tables, each of which will require
> > its own mempool allocation. This RFC is not about how to optimize the
> > application usage of mempool nor about how to improve the mempool
> > implementation based on memzone. It is about how to make the max
> > memzone definition - build-time or run-time customized.
> >
> > I would like to suggest three options.
> >
> > Option 1
> > ========
> > Add a Meson option in meson options.txt and remove the
> RTE_MAX_MEMZONE
> > definition from config/rte_config.h
> >
> [...]
> >
> > Option 2
> > ========
> > Use Meson setup -Dc_args="-DRTE_MAX_MEMZONE=XXX" and make
> > RTE_MAX_MEMZONE conditional in config/rte_config.h
> >
> > For example, see the code of this commit.
> >
> > Option 3
> > ========
> > Add a function which must be called before rte_eal_init():
> > void rte_memzone_set_max(int max) {memzone_max = max;} If not called,
> > the default memzone (RTE_MAX_MEMZONE) is used.
> >
> > With this option there is no need to recompile DPDK and it allows
> > using an in-box packaged DPDK.
> [...]
>
> Ideally, there should be no limitation at all.
> I vote for some compile-time solution for now with a plan to remove the
> restriction inside EAL later.
> Option 2 does not expose a user-facing option that would be obsoleted
> anyway, so it seems preferable to me, but Option 1 is also OK and consistent.
>
> `RTE_MAX_MEMZONE` is needed currently, because `struct rte_memzone`
> are stored in `rte_fbarray` (mapped file-backed array) with a fixed capacity.
> Unlike e.g. `rte_eth_devices`, this is not used for efficient access by index
> and
> is not even exposed to PMDs, so the storage can be changed painlessly.
> In DPDK, only net/qede uses this constant and also for slow-path
> bookkeeping.
