Re: [PATCH v2 3/3] mm/slub: Use percpu partial free counter

[Christoph Lameter]

On Wed, 3 Mar 2021, Matthew Wilcox wrote:

> On Tue, Mar 02, 2021 at 10:14:53AM +0100, Christoph Lameter wrote:
> > On Mon, 10 Aug 2020, Xunlei Pang wrote:
> > > -	atomic_long_t partial_free_objs;
> > > +	atomic_long_t __percpu *partial_free_objs;
> >
> > A percpu counter is never atomic. Just use unsigned long and use this_cpu
> > operations for this thing. That should cut down further on the overhead.
>
> What about allocations from interrupt context?  Should this be a local_t
> instead?

Can this be allocated in an interrupt context?

And I am not sure how local_t relates to that? Percpu counters can be used
in an interrupt context without the overhead of the address calculations
that are required by a local_t.