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In-Reply-To: <c1fd166d42ded9cc9839eb2722174549059dd36f.1559129225.git.vpillai@digitalocean.com>
From:   Peter Oskolkov <posk@posk.io>
Date:   Wed, 29 May 2019 14:02:30 -0700
Message-ID: <CAFTs51V+z-zjGaMAysdR4pPPKJO4rWVekjzRk3mc+wMwwYbvDg@mail.gmail.com>
Subject: Re: [RFC PATCH v3 16/16] sched: Debug bits...
To:     Vineeth Remanan Pillai <vpillai@digitalocean.com>
Cc:     Nishanth Aravamudan <naravamudan@digitalocean.com>,
        Julien Desfossez <jdesfossez@digitalocean.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Tim Chen <tim.c.chen@linux.intel.com>, mingo@kernel.org,
        tglx@linutronix.de, pjt@google.com, torvalds@linux-foundation.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        subhra.mazumdar@oracle.com, fweisbec@gmail.com,
        keescook@chromium.org, kerrnel@google.com,
        Phil Auld <pauld@redhat.com>, Aaron Lu <aaron.lwe@gmail.com>,
        Aubrey Li <aubrey.intel@gmail.com>,
        Valentin Schneider <valentin.schneider@arm.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>
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On Wed, May 29, 2019 at 1:37 PM Vineeth Remanan Pillai
<vpillai@digitalocean.com> wrote:
>
> From: Peter Zijlstra <peterz@infradead.org>
>
> Not-Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

No commit message, not-signed-off-by...

> ---
>  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 5b8223c9a723..90655c9ad937 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -92,6 +92,10 @@ 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;
>
> @@ -246,6 +250,8 @@ 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)
> @@ -254,6 +260,8 @@ 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)
> @@ -3707,6 +3715,14 @@ 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;
>         }
>
> @@ -3786,6 +3802,9 @@ 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;
>                         }
>
> @@ -3794,6 +3813,9 @@ 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
> @@ -3810,6 +3832,8 @@ 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)
> @@ -3837,6 +3861,7 @@ 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
> @@ -3862,11 +3887,20 @@ 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:
> @@ -3905,6 +3939,10 @@ 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);
> @@ -6501,6 +6539,8 @@ 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
>