[PATCH] doc: clarify mempool striding optimisation on Arm

[Bruce Richardson]

On Tue, Jul 16, 2024 at 07:25:41PM -0700, Stephen Hemminger wrote:
> On Mon, 15 Jul 2024 15:44:20 +0100
> Jack Bond-Preston <jack.bond-preston at foss.arm.com> wrote:
> 
> > The mempool memory channel striding optimisation is not necessary on
> > Arm platforms.
> > Update the Programmer's Guide's mempool section to clarify this.
> > 
> > Signed-off-by: Jack Bond-Preston <jack.bond-preston at foss.arm.com>
> > Reviewed-by: Wathsala Vithanage <wathsala.vithanage at arm.com>
> > ---
> 
> The whole memory channels argument has been a problem from day 0 of DPDK.
> There is no good way to find it from the OS, and it was never clear how much impact
> it had anyway. It would simplify users experience if it was deprecated or at least
> not required and rarely used.

The default for mempools (at least on x86) is set to 4 which is a
reasonable value, and so specifying memory channels is not really required
for running DPDK in most cases (I never use the -n flag when running tests
myself). While I don't think we should deprecate the option, I feel it
should be removed from our examples and scripts.  Hopefully in future a
method of determining memory channels from code can be come up with that we
can use, but in the meantime using a sane default I feel is good enough.

/Bruce