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

[Andrew Morton]

On Mon, 12 Feb 2018 16:24:25 -0800 (PST) David Rientjes <rientjes@xxxxxxxxxx> wrote:

> Both kernelcore= and movablecore= can be used to define the amount of
> ZONE_NORMAL and ZONE_MOVABLE on a system, respectively.  This requires
> the system memory capacity to be known when specifying the command line,
> however.
> 
> This introduces the ability to define both kernelcore= and movablecore=
> as a percentage of total system memory.  This is convenient for systems
> software that wants to define the amount of ZONE_MOVABLE, for example, as
> a proportion of a system's memory rather than a hardcoded byte value.
> 
> To define the percentage, the final character of the parameter should be
> a '%'.

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.