OpenBMC kernel and CONFIG_PREEMPT

[Joel Stanley]

On Fri, 7 Apr 2023 at 22:07, Zev Weiss <zweiss at equinix.com> wrote:
>
> On Fri, Apr 07, 2023 at 01:12:21PM PDT, William Kennington wrote:
> >I just looked again, AFAICT it was never enabled on aspeed or npcm7xx, just
> >the new 8xx part. Hopefully someone else with aspeed chips will confirm
> >from their actual `.config`
> >
>
> Yeah, I'm pretty sure that's correct -- my aspeed builds already show:
>
>     $ zcat /proc/config.gz | grep PREEMPT
>     CONFIG_PREEMPT_NONE_BUILD=y
>     CONFIG_PREEMPT_NONE=y
>     # CONFIG_PREEMPT_VOLUNTARY is not set
>     # CONFIG_PREEMPT is not set
>
> Incidentally, out of curiosity I tried booting kernels built with
> CONFIG_PREEMPT=y and didn't see any major changes in boot performance on
> either ast2500 or ast2400.

Thanks for collecting some data. If someone wants to do the same test
on an ast2600 that would be handy.

I came across the commit today too, thanks for posting it to the list Patrick.

We should keep this in mind for future BMCs as they move to arm64 cores.

Cheers,

Joel