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Subject[RFC PATCH 16/16] sched: Debug bits...
Date
From: Peter Zijlstra <peterz@infradead.org>

Not-Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/sched/core.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2ec56970d6bb..0362102fa3d2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -105,6 +105,10 @@ static inline bool prio_less(struct task_struct *a, struct task_struct *b)

int pa = __task_prio(a), pb = __task_prio(b);

+ trace_printk("(%s/%d;%d,%Lu,%Lu) ?< (%s/%d;%d,%Lu,%Lu)\n",
+ a->comm, a->pid, pa, a->se.vruntime, a->dl.deadline,
+ b->comm, b->pid, pb, b->se.vruntime, b->dl.deadline);
+
if (-pa < -pb)
return true;

@@ -302,12 +306,16 @@ static void __sched_core_enable(void)

static_branch_enable(&__sched_core_enabled);
stop_machine(__sched_core_stopper, (void *)true, NULL);
+
+ printk("core sched enabled\n");
}

static void __sched_core_disable(void)
{
stop_machine(__sched_core_stopper, (void *)false, NULL);
static_branch_disable(&__sched_core_enabled);
+
+ printk("core sched disabled\n");
}

void sched_core_get(void)
@@ -4477,6 +4485,14 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
put_prev_task(rq, prev);
set_next_task(rq, next);
}
+
+ trace_printk("pick pre selected (%u %u %u): %s/%d %lx\n",
+ rq->core->core_task_seq,
+ rq->core->core_pick_seq,
+ rq->core_sched_seq,
+ next->comm, next->pid,
+ next->core_cookie);
+
return next;
}

@@ -4551,6 +4567,9 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
*/
if (i == cpu && !need_sync && !p->core_cookie) {
next = p;
+ trace_printk("unconstrained pick: %s/%d %lx\n",
+ next->comm, next->pid, next->core_cookie);
+
goto done;
}

@@ -4559,6 +4578,9 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)

rq_i->core_pick = p;

+ trace_printk("cpu(%d): selected: %s/%d %lx\n",
+ i, p->comm, p->pid, p->core_cookie);
+
/*
* If this new candidate is of higher priority than the
* previous; and they're incompatible; we need to wipe
@@ -4575,6 +4597,8 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
rq->core->core_cookie = p->core_cookie;
max = p;

+ trace_printk("max: %s/%d %lx\n", max->comm, max->pid, max->core_cookie);
+
if (old_max) {
for_each_cpu(j, smt_mask) {
if (j == i)
@@ -4602,6 +4626,7 @@ next_class:;
rq->core->core_pick_seq = rq->core->core_task_seq;
next = rq->core_pick;
rq->core_sched_seq = rq->core->core_pick_seq;
+ trace_printk("picked: %s/%d %lx\n", next->comm, next->pid, next->core_cookie);

/*
* Reschedule siblings
@@ -4624,11 +4649,20 @@ next_class:;
if (i == cpu)
continue;

- if (rq_i->curr != rq_i->core_pick)
+ if (rq_i->curr != rq_i->core_pick) {
+ trace_printk("IPI(%d)\n", i);
resched_curr(rq_i);
+ }

/* Did we break L1TF mitigation requirements? */
- WARN_ON_ONCE(!cookie_match(next, rq_i->core_pick));
+ if (unlikely(!cookie_match(next, rq_i->core_pick))) {
+ trace_printk("[%d]: cookie mismatch. %s/%d/0x%lx/0x%lx\n",
+ rq_i->cpu, rq_i->core_pick->comm,
+ rq_i->core_pick->pid,
+ rq_i->core_pick->core_cookie,
+ rq_i->core->core_cookie);
+ WARN_ON_ONCE(1);
+ }
}

done:
@@ -4667,6 +4701,10 @@ static bool try_steal_cookie(int this, int that)
if (p->core_occupation > dst->idle->core_occupation)
goto next;

+ trace_printk("core fill: %s/%d (%d->%d) %d %d %lx\n",
+ p->comm, p->pid, that, this,
+ p->core_occupation, dst->idle->core_occupation, cookie);
+
p->on_rq = TASK_ON_RQ_MIGRATING;
deactivate_task(src, p, 0);
set_task_cpu(p, this);
@@ -7305,6 +7343,8 @@ int sched_cpu_starting(unsigned int cpu)
WARN_ON_ONCE(rq->core && rq->core != core_rq);
rq->core = core_rq;
}
+
+ printk("core: %d -> %d\n", cpu, cpu_of(core_rq));
#endif /* CONFIG_SCHED_CORE */

sched_rq_cpu_starting(cpu);
--
2.17.1
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