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On Tue, Jun 03, 2025 at 10:22:01AM +0200, Andrea Righi wrote: > In the idle CPU selection logic, attempting cross-node searches adds > unnecessary complexity when CONFIG_NUMA is disabled. > > Since there's no meaningful concept of nodes in this case, simplify the > logic by restricting the idle CPU search to the current node only. > > Fixes: 48849271e6611 ("sched_ext: idle: Per-node idle cpumasks") > Signed-off-by: Andrea Righi > --- > kernel/sched/ext_idle.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/kernel/sched/ext_idle.c b/kernel/sched/ext_idle.c > index 66da03cc0b338..8660d9ae40169 100644 > --- a/kernel/sched/ext_idle.c > +++ b/kernel/sched/ext_idle.c > @@ -138,6 +138,7 @@ static s32 pick_idle_cpu_in_node(const struct cpumask *cpus_allowed, int node, u > goto retry; > } > > +#ifdef CONFIG_NUMA It would be more natural if you move this inside the function body, and not duplicate the function declaration. > /* > * Tracks nodes that have not yet been visited when searching for an idle > * CPU across all available nodes. > @@ -186,6 +187,13 @@ static s32 pick_idle_cpu_from_online_nodes(const struct cpumask *cpus_allowed, i > > return cpu; > } > +#else > +static inline s32 > +pick_idle_cpu_from_online_nodes(const struct cpumask *cpus_allowed, int node, u64 flags) > +{ > + return -EBUSY; > +} This is misleading errno. The system is nut busy, it is disabled. If it was a syscall, I would say you should return ENOSYS. ENODATA is another candidate. Or you have a special policy for the subsystem/ The above pick_idle_cpu_in_node() doesn't have CONFIG_NUMA protection as well. Is it safe against CONFIG_NUMA? > +#endif > > /* > * Find an idle CPU in the system, starting from @node. > -- > 2.49.0