diff options
| author | Changwoo Min <changwoo@igalia.com> | 2025-01-31 16:09:29 +0900 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2025-02-02 07:23:18 -1000 |
| commit | f7f6142107f0e0dd4a2b041116461a049ca18cb0 (patch) | |
| tree | 0353dac975cfb1e2ac2ed1810ebe1c61e3738b0c | |
| parent | 17103b8504de68958b0ff412ed2ae2e6484fa65f (diff) | |
sched_ext: Add an event, SCX_EV_SELECT_CPU_FALLBACK
Add a core event, SCX_EV_SELECT_CPU_FALLBACK, which represents how many times
ops.select_cpu() returns a CPU that the task can't use.
__scx_add_event() is used since the caller holds an rq lock,
so the preemption has already been disabled.
Signed-off-by: Changwoo Min <changwoo@igalia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
| -rw-r--r-- | include/linux/sched/ext.h | 1 | ||||
| -rw-r--r-- | kernel/sched/ext.c | 13 |
2 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h index 1d70a9867fb1..f7545430a548 100644 --- a/include/linux/sched/ext.h +++ b/include/linux/sched/ext.h @@ -146,6 +146,7 @@ struct sched_ext_entity { u32 weight; s32 sticky_cpu; s32 holding_cpu; + s32 selected_cpu; u32 kf_mask; /* see scx_kf_mask above */ struct task_struct *kf_tasks[2]; /* see SCX_CALL_OP_TASK() */ atomic_long_t ops_state; diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 4e28e88e88d4..f80c8dc024a7 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -1444,6 +1444,11 @@ static struct task_struct *scx_task_iter_next_locked(struct scx_task_iter *iter) * Collection of event counters. Event types are placed in descending order. */ struct scx_event_stats { + /* + * If ops.select_cpu() returns a CPU which can't be used by the task, + * the core scheduler code silently picks a fallback CPU. + */ + u64 SCX_EV_SELECT_CPU_FALLBACK; }; /* @@ -2170,6 +2175,10 @@ static void enqueue_task_scx(struct rq *rq, struct task_struct *p, int enq_flags do_enqueue_task(rq, p, enq_flags, sticky_cpu); out: rq->scx.flags &= ~SCX_RQ_IN_WAKEUP; + + if ((enq_flags & SCX_ENQ_CPU_SELECTED) && + unlikely(cpu_of(rq) != p->scx.selected_cpu)) + __scx_add_event(SCX_EV_SELECT_CPU_FALLBACK, 1); } static void ops_dequeue(struct task_struct *p, u64 deq_flags) @@ -3240,6 +3249,7 @@ static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flag cpu = SCX_CALL_OP_TASK_RET(SCX_KF_ENQUEUE | SCX_KF_SELECT_CPU, select_cpu, p, prev_cpu, wake_flags); + p->scx.selected_cpu = cpu; *ddsp_taskp = NULL; if (ops_cpu_valid(cpu, "from ops.select_cpu()")) return cpu; @@ -3250,6 +3260,7 @@ static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flag s32 cpu; cpu = scx_select_cpu_dfl(p, prev_cpu, wake_flags, &found); + p->scx.selected_cpu = cpu; if (found) { p->scx.slice = SCX_SLICE_DFL; p->scx.ddsp_dsq_id = SCX_DSQ_LOCAL; @@ -4957,6 +4968,7 @@ static void scx_dump_state(struct scx_exit_info *ei, size_t dump_len) dump_line(&s, "--------------"); scx_bpf_events(&events, sizeof(events)); + scx_dump_event(s, &events, SCX_EV_SELECT_CPU_FALLBACK); if (seq_buf_has_overflowed(&s) && dump_len >= sizeof(trunc_marker)) memcpy(ei->dump + dump_len - sizeof(trunc_marker), @@ -7090,6 +7102,7 @@ __bpf_kfunc void scx_bpf_events(struct scx_event_stats *events, memset(&e_sys, 0, sizeof(e_sys)); for_each_possible_cpu(cpu) { e_cpu = per_cpu_ptr(&event_stats_cpu, cpu); + scx_agg_event(&e_sys, e_cpu, SCX_EV_SELECT_CPU_FALLBACK); } /* |