Thanks, We met an issue that a normal thread can't get cpu, And at this moment, we found 'sched: RT throttling activated' log.
So I think this patch is useful for such issue. Could I get more comments? Thanks in advance -----Original Message----- From: Steven Rostedt [mailto:rost...@goodmis.org] Sent: Thursday, December 03, 2020 10:40 PM To: tianxianting (RD) <tian.xiant...@h3c.com> Cc: mi...@redhat.com; pet...@infradead.org; juri.le...@redhat.com; vincent.guit...@linaro.org; dietmar.eggem...@arm.com; bseg...@google.com; mgor...@suse.de; linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/rt: Print curr when RT throttling activated On Thu, 3 Dec 2020 15:51:29 +0800 Xianting Tian <tian.xiant...@h3c.com> wrote: > We may meet the issue, that one RT thread occupied the cpu by > 950ms/1s, The RT thread maybe is a business thread or other unknown thread. > > Currently, it only outputs the print "sched: RT throttling activated" > when RT throttling happen. It is hard to know what is the RT thread, > For further analysis, we need add more prints. > > This patch is to print current RT task when RT throttling activated, > It help us to know what is the RT thread in the first time. I think this can be useful information to include. Acked-by: Steven Rostedt (VMware) <rost...@goodmis.org> -- Steve > > Signed-off-by: Xianting Tian <tian.xiant...@h3c.com> > --- > kernel/sched/rt.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index > f215eea6a..8913f38cb 100644 > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -946,7 +946,7 @@ static inline int rt_se_prio(struct sched_rt_entity > *rt_se) > return rt_task_of(rt_se)->prio; > } > > -static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq) > +static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq, struct > +task_struct *curr) > { > u64 runtime = sched_rt_runtime(rt_rq); > > @@ -970,7 +970,8 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq) > */ > if (likely(rt_b->rt_runtime)) { > rt_rq->rt_throttled = 1; > - printk_deferred_once("sched: RT throttling > activated\n"); > + printk_deferred_once("sched: RT throttling activated > (curr: pid %d, comm %s)\n", > + curr->pid, curr->comm); > } else { > /* > * In case we did anyway, make it go away, @@ -1026,7 > +1027,7 @@ > static void update_curr_rt(struct rq *rq) > if (sched_rt_runtime(rt_rq) != RUNTIME_INF) { > raw_spin_lock(&rt_rq->rt_runtime_lock); > rt_rq->rt_time += delta_exec; > - if (sched_rt_runtime_exceeded(rt_rq)) > + if (sched_rt_runtime_exceeded(rt_rq, curr)) > resched_curr(rq); > raw_spin_unlock(&rt_rq->rt_runtime_lock); > }
