sched_ext: Test scx_has_subs() inline before calling sub-sched hooks

scx_reenq_reject(), scx_process_sync_ecaps() and scx_resolve_local_dsq()
return early if there are no sub-schedulers, but clang emits the full
prologue before the static branch. Without sub-schedulers, we still pay
for a call and for saving and restoring up to six registers, on every
wakeup, dispatch and local DSQ insert.

Let's move the scx_has_subs() test into inline wrappers, so that these
calls go away completely. The wrappers keep lockdep_assert_rq_held().

In a pinned perf bench sched pipe test on x86-64 with clang 22, this
reduced kernel instructions by 52-54 per context switch with scx_simple,
scx_lavd and scx_layered.

No functional change intended.

Signed-off-by: Usama Arif <usama.arif@linux.dev>
Signed-off-by: Tejun Heo <tj@kernel.org>

0 files changed, 0 insertions, 0 deletions