Re: [PATCH 28/32] sched_ext: Implement core-sched support

Tejun Heo
2023-04-21T14:31:32Z

Hello, Andrea.

On Thu, Apr 20, 2023 at 09:56:11PM +0200, Andrea Righi wrote:
> On Fri, Mar 17, 2023 at 11:33:29AM -1000, Tejun Heo wrote:
> ...
> >
> > +static int balance_scx(struct rq *rq, struct task_struct *prev,
> > + struct rq_flags *rf)
> > +{
> > + int ret;
> > +
> > + ret = balance_one(rq, prev, rf, true);
> > +
> > + /*
> > + * When core-sched is enabled, this ops.balance() call will be followed
> > + * by put_prev_scx() and pick_task_scx() on this CPU and pick_task_scx()
> > + * on the SMT siblings. Balance the siblings too.
> > + */
> > + if (sched_core_enabled(rq)) {
> > + const struct cpumask *smt_mask = cpu_smt_mask(cpu_of(rq));
>
> balance_scx() should be a no-op if CONFIG_SCHED_SMT is undefined or we
> may get a build error here.
>
> For example with a minimal ppc64le config (and CONFIG_SCHED_SMT off) I
> can reproduce this:
>
> ./arch/powerpc/include/asm/smp.h:139:22: error: implicit declaration of function 'cpu_smt_mask'; did you mean 'cpu_cpu_mask'? [-Werror=implicit-function-declaration]
>
> So maybe have something like this (or similar):
>
> #ifdef CONFIG_SCHED_SMT
> ...
> #else
> static inline int balance_scx(struct rq *rq, struct task_struct *prev,
> struct rq_flags *rf)
> {
> return 0
> }
> #endif

Will fix.

Thank you.

--
tejun