Re: [patch 1/2] mm, page_alloc: extend kernelcore and movablecore for percent

[Andrew Morton]

On Tue, 13 Feb 2018 15:55:11 -0800 (PST) David Rientjes <rientjes@xxxxxxxxxx> wrote:

> > 
> > Is this fine-grained enough?  We've had percentage-based tunables in
> > the past, and 10 years later when systems are vastly larger, 1% is too
> > much.
> > 
> 
> They still have the (current) ability to define the exact amount of bytes 
> down to page sized granularity, whereas 1% would yield 40GB on a 4TB 
> system.  I'm not sure that people will want any finer-grained control if 
> defining the proportion of the system for kernelcore.  They do have the 
> ability with the existing interface, though, if they want to be that 
> precise.
> 
> (This is a cop out for not implementing some fractional percentage parser, 
>  although that would be possible as a more complete solution.)

And the interface which you've proposed can be seamlessly extended to
accept 0.07%, so not a problem.