sched_ext: Add an event, SCX_EV_BYPASS_DISPATCH

Add a core event, SCX_EV_BYPASS_DISPATCH, which represents how many
tasks have been dispatched in the bypass mode.

__scx_add_event() is used since the caller holds an rq lock or
p->pi_lock, so the preemption has already been disabled.

Signed-off-by: Changwoo Min <changwoo@igalia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 377c2e99cf4fa0984434ea67533fc014fbec81c8..0ed2db44ae335fd5ff10335e5efec373958176e1 100644 (file)
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1468,6 +1468,11 @@ struct scx_event_stats {
         */
        u64             SCX_EV_ENQ_SKIP_EXITING;
 
+       /*
+        * The number of tasks dispatched in the bypassing mode.
+        */
+       u64             SCX_EV_BYPASS_DISPATCH;
+
        /*
         * The number of times the bypassing mode has been activated.
         */
@@ -2071,8 +2076,10 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
        if (!scx_rq_online(rq))
                goto local;
 
-       if (scx_rq_bypassing(rq))
+       if (scx_rq_bypassing(rq)) {
+               __scx_add_event(SCX_EV_BYPASS_DISPATCH, 1);
                goto global;
+       }
 
        if (p->scx.ddsp_dsq_id != SCX_DSQ_INVALID)
                goto direct;
@@ -3253,6 +3260,8 @@ bool scx_prio_less(const struct task_struct *a, const struct task_struct *b,
 
 static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flags)
 {
+       bool rq_bypass;
+
        /*
         * sched_exec() calls with %WF_EXEC when @p is about to exec(2) as it
         * can be a good migration opportunity with low cache and memory
@@ -3266,7 +3275,8 @@ static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flag
        if (unlikely(wake_flags & WF_EXEC))
                return prev_cpu;
 
-       if (SCX_HAS_OP(select_cpu) && !scx_rq_bypassing(task_rq(p))) {
+       rq_bypass = scx_rq_bypassing(task_rq(p));
+       if (SCX_HAS_OP(select_cpu) && !rq_bypass) {
                s32 cpu;
                struct task_struct **ddsp_taskp;
 
@@ -3292,6 +3302,9 @@ static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flag
                        p->scx.slice = SCX_SLICE_DFL;
                        p->scx.ddsp_dsq_id = SCX_DSQ_LOCAL;
                }
+
+               if (rq_bypass)
+                       __scx_add_event(SCX_EV_BYPASS_DISPATCH, 1);
                return cpu;
        }
 }
@@ -5000,6 +5013,7 @@ static void scx_dump_state(struct scx_exit_info *ei, size_t dump_len)
        scx_dump_event(s, &events, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
        scx_dump_event(s, &events, SCX_EV_DISPATCH_KEEP_LAST);
        scx_dump_event(s, &events, SCX_EV_ENQ_SKIP_EXITING);
+       scx_dump_event(s, &events, SCX_EV_BYPASS_DISPATCH);
        scx_dump_event(s, &events, SCX_EV_BYPASS_ACTIVATE);
 
        if (seq_buf_has_overflowed(&s) && dump_len >= sizeof(trunc_marker))
@@ -7138,6 +7152,7 @@ __bpf_kfunc void scx_bpf_events(struct scx_event_stats *events,
                scx_agg_event(&e_sys, e_cpu, SCX_EV_DISPATCH_LOCAL_DSQ_OFFLINE);
                scx_agg_event(&e_sys, e_cpu, SCX_EV_DISPATCH_KEEP_LAST);
                scx_agg_event(&e_sys, e_cpu, SCX_EV_ENQ_SKIP_EXITING);
+               scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_DISPATCH);
                scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_ACTIVATE);
        }