diff options
Diffstat (limited to 'tools/sched_ext/scx_qmap.bpf.c')
| -rw-r--r-- | tools/sched_ext/scx_qmap.bpf.c | 37 |
1 files changed, 36 insertions, 1 deletions
diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c index 879fc9c788e5..4a87377558c8 100644 --- a/tools/sched_ext/scx_qmap.bpf.c +++ b/tools/sched_ext/scx_qmap.bpf.c @@ -11,6 +11,8 @@ * * - BPF-side queueing using PIDs. * - Sleepable per-task storage allocation using ops.prep_enable(). + * - Using ops.cpu_release() to handle a higher priority scheduling class taking + * the CPU away. * * This scheduler is primarily for demonstration and testing of sched_ext * features and unlikely to be useful for actual workloads. @@ -90,7 +92,7 @@ struct { } cpu_ctx_stor SEC(".maps"); /* Statistics */ -u64 nr_enqueued, nr_dispatched, nr_dequeued; +u64 nr_enqueued, nr_dispatched, nr_reenqueued, nr_dequeued; s32 BPF_STRUCT_OPS(qmap_select_cpu, struct task_struct *p, s32 prev_cpu, u64 wake_flags) @@ -164,6 +166,22 @@ void BPF_STRUCT_OPS(qmap_enqueue, struct task_struct *p, u64 enq_flags) return; } + /* + * If the task was re-enqueued due to the CPU being preempted by a + * higher priority scheduling class, just re-enqueue the task directly + * on the global DSQ. As we want another CPU to pick it up, find and + * kick an idle CPU. + */ + if (enq_flags & SCX_ENQ_REENQ) { + s32 cpu; + + scx_bpf_dispatch(p, SHARED_DSQ, 0, enq_flags); + cpu = scx_bpf_pick_idle_cpu(p->cpus_ptr, 0); + if (cpu >= 0) + scx_bpf_kick_cpu(cpu, SCX_KICK_IDLE); + return; + } + ring = bpf_map_lookup_elem(&queue_arr, &idx); if (!ring) { scx_bpf_error("failed to find ring %d", idx); @@ -257,6 +275,22 @@ void BPF_STRUCT_OPS(qmap_dispatch, s32 cpu, struct task_struct *prev) } } +void BPF_STRUCT_OPS(qmap_cpu_release, s32 cpu, struct scx_cpu_release_args *args) +{ + u32 cnt; + + /* + * Called when @cpu is taken by a higher priority scheduling class. This + * makes @cpu no longer available for executing sched_ext tasks. As we + * don't want the tasks in @cpu's local dsq to sit there until @cpu + * becomes available again, re-enqueue them into the global dsq. See + * %SCX_ENQ_REENQ handling in qmap_enqueue(). + */ + cnt = scx_bpf_reenqueue_local(); + if (cnt) + __sync_fetch_and_add(&nr_reenqueued, cnt); +} + s32 BPF_STRUCT_OPS(qmap_init_task, struct task_struct *p, struct scx_init_task_args *args) { @@ -339,6 +373,7 @@ SCX_OPS_DEFINE(qmap_ops, .enqueue = (void *)qmap_enqueue, .dequeue = (void *)qmap_dequeue, .dispatch = (void *)qmap_dispatch, + .cpu_release = (void *)qmap_cpu_release, .init_task = (void *)qmap_init_task, .dump = (void *)qmap_dump, .dump_cpu = (void *)qmap_dump_cpu, |