Re: [PATCH] arm64: Kconfig: Increase NR_CPUS default to 512

[Catalin Marinas]

On Mon, Jan 11, 2021 at 10:03:18AM -0800, Randy Dunlap wrote:
> On 1/11/21 9:57 AM, Vanshidhar Konda wrote:
> > On Mon, Jan 11, 2021 at 10:56:36AM +0000, Will Deacon wrote:
> >> On Sat, Jan 09, 2021 at 09:36:15PM -0800, vanshikonda@xxxxxxxxxxxxxxxxxxxxxx wrote:
> >>> From: Vanshidhar Konda <vanshikonda@xxxxxxxxxxxxxxxxxxxxxx>
> >>>
> >>> Increase the default value of NR_CPUS to 512 from 256. This will
> >>> enable the defconfig kernel to support platforms that have upto
> >>> 512 cores.
> >>
> >> Do we already support such a platform, and what is it? I'm fine with bumping.
> >> the number, it's just nice to be able to say specifically _why_ we're dong
> >> it.
> > 
> > I'm not aware of any publicly available systems that run into the 256
> > core limitation. At Ampere we have internal systems that would benefit
> > from this change as they support more than 256 cores.
> 
> But what does that have to do with the default value?
> Do you expect to run defconfig kernels?
> I don't ever expect that.

We still aim for the arm64 defconfig to run on all supported SoCs, even
if not optimally. Distros indeed tweak the config to their needs.

-- 
Catalin