On Fri, Dec 20, 2024 at 09:56:54AM -0800, Christoph Lameter (Ampere) wrote:
> On Thu, 19 Dec 2024, Mitchell Levy wrote:
>
> > + let mut native: i64 = 0;
> > + let mut pcpu: PerCpuRef<i64> = unsafe { unsafe_get_per_cpu_ref!(PERCPU, CpuGuard::new()) };
>
> A bit complex.
>
> > + native += -1;
> > + *pcpu += -1;
> > + assert!(native == *pcpu && native == -1);
> > +
> > + native += 1;
> > + *pcpu += 1;
> > + assert!(native == *pcpu && native == 0);
> > +
>
> That's pretty straightforward..... But is there no symbolic access to the
> per cpu namespace? How would you access the kernel per cpu variables
> defined in C?
>
FWIW, there is a declare_extern_per_cpu!() marco in patch #1, and
Mitchell used it to access this_cpu_off (defined in C).
Maybe we want to see an example here?
Regards,
Boqun
> How do you go about using per cpu atomics like
>
> this_cpu_inc(nr_dentry_unused);
>
>
