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sched_ext: Use schedule_deferred_locked() in schedule_dsq_reenq()

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schedule_dsq_reenq() always uses schedule_deferred() which falls back to
irq_work. However, callers like schedule_reenq_local() already hold the
target rq lock, and scx_bpf_dsq_reenq() may hold it via the ops callback.

Add a locked_rq parameter so schedule_dsq_reenq() can use
schedule_deferred_locked() when the target rq is already held. The locked
variant can use cheaper paths (balance callbacks, wakeup hooks) instead of
always bouncing through irq_work.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
This commit is contained in:
Tejun Heo 2026-03-13 09:43:23 -10:00
parent 3229ac4a5e
commit 238eba8c21
1 changed files with 15 additions and 9 deletions
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24
kernel/sched/ext.c
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@ -1218,8 +1218,10 @@ static void schedule_deferred_locked(struct rq *rq)
}
static void schedule_dsq_reenq(struct scx_sched *sch, struct scx_dispatch_q *dsq,
u64 reenq_flags)
u64 reenq_flags, struct rq *locked_rq)
{
struct rq *rq;
/*
* Allowing reenqueues doesn't make sense while bypassing. This also
* blocks from new reenqueues to be scheduled on dead scheds.
@ -1228,7 +1230,8 @@ static void schedule_dsq_reenq(struct scx_sched *sch, struct scx_dispatch_q *dsq
return;
if (dsq->id == SCX_DSQ_LOCAL) {
struct rq *rq = container_of(dsq, struct rq, scx.local_dsq);
rq = container_of(dsq, struct rq, scx.local_dsq);
struct scx_sched_pcpu *sch_pcpu = per_cpu_ptr(sch->pcpu, cpu_of(rq));
struct scx_deferred_reenq_local *drl = &sch_pcpu->deferred_reenq_local;
@ -1247,10 +1250,9 @@ static void schedule_dsq_reenq(struct scx_sched *sch, struct scx_dispatch_q *dsq
list_move_tail(&drl->node, &rq->scx.deferred_reenq_locals);
WRITE_ONCE(drl->flags, drl->flags | reenq_flags);
}
schedule_deferred(rq);
} else if (!(dsq->id & SCX_DSQ_FLAG_BUILTIN)) {
struct rq *rq = this_rq();
rq = this_rq();
struct scx_dsq_pcpu *dsq_pcpu = per_cpu_ptr(dsq->pcpu, cpu_of(rq));
struct scx_deferred_reenq_user *dru = &dsq_pcpu->deferred_reenq_user;
@ -1269,11 +1271,15 @@ static void schedule_dsq_reenq(struct scx_sched *sch, struct scx_dispatch_q *dsq
list_move_tail(&dru->node, &rq->scx.deferred_reenq_users);
WRITE_ONCE(dru->flags, dru->flags | reenq_flags);
}
schedule_deferred(rq);
} else {
scx_error(sch, "DSQ 0x%llx not allowed for reenq", dsq->id);
return;
}
if (rq == locked_rq)
schedule_deferred_locked(rq);
else
schedule_deferred(rq);
}
static void schedule_reenq_local(struct rq *rq, u64 reenq_flags)
@ -1283,7 +1289,7 @@ static void schedule_reenq_local(struct rq *rq, u64 reenq_flags)
if (WARN_ON_ONCE(!root))
return;
schedule_dsq_reenq(root, &rq->scx.local_dsq, reenq_flags);
schedule_dsq_reenq(root, &rq->scx.local_dsq, reenq_flags, rq);
}
/**
@ -8845,7 +8851,7 @@ __bpf_kfunc void scx_bpf_dsq_reenq(u64 dsq_id, u64 reenq_flags,
reenq_flags |= SCX_REENQ_ANY;
dsq = find_dsq_for_dispatch(sch, this_rq(), dsq_id, smp_processor_id());
schedule_dsq_reenq(sch, dsq, reenq_flags);
schedule_dsq_reenq(sch, dsq, reenq_flags, scx_locked_rq());
}
/**