Re: nr_cpu_ids vs AMD 3970x(32 physical CPUs)

[Matthew Wilcox]

On Fri, Jul 03, 2020 at 11:20:47PM +0200, Uladzislau Rezki wrote:
> Some background:
> Actually i have been thinking about making vmalloc address space to
> be per-CPU, i.e. divide it to per-CPU address space making an allocation
> lock-less. It will eliminate a high lock contention. When i have done
> a prototype i noticed and realized that there is a silly issue with
> nr_cpu_ids on some systems.

vfree() may happen on a different CPU from the one which called vmalloc(),
so I'm not sure you're going to get as large a win as you think you will.