Messages in this thread |  | | Date | Mon, 12 Dec 2022 02:05:40 +0000 | From | "Yajun Deng" <> | Subject | Re: [PATCH] sched/rt: Add pid and comm when RT throttling activated |
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December 10, 2022 5:36 AM, "Steven Rostedt" <rostedt@goodmis.org> wrote:
> On Tue, 6 Dec 2022 16:36:41 +0800 > Yajun Deng <yajun.deng@linux.dev> wrote: > >> It is difficult to know which process consumes time when RT throttling >> activated. >> >> So add pid and comm for this case. > > Unfortunately, that only shows the process that "broke the camel's > back"[1]. The things is, it is the amount of time *all* RT tasks use to > trigger throttling. You are only printing the task that the throttling > occurred on. > > Try running https://rostedt.org/code/migrate.c . It will create a bunch of > RT tasks, and they all will throttle once it hits 950ms ever second. > > trace-cmd record -e sched_switch ./migrate > kernelshark > > Then plot all the migrate tasks. > > The above will demonstrate it very well.
Thanks for your patient answer, I'll test it.
> > -- Steve > > [1] https://en.wikipedia.org/wiki/Straw_that_broke_the_camel's_back > >> Signed-off-by: Yajun Deng <yajun.deng@linux.dev> >> --- >> kernel/sched/rt.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c >> index ed2a47e4ddae..1f267ab1b59a 100644 >> --- a/kernel/sched/rt.c >> +++ b/kernel/sched/rt.c >> @@ -1012,6 +1012,7 @@ static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq) >> >> if (rt_rq->rt_time > runtime) { >> struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq); >> + struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr; >> >> /* >> * Don't actually throttle groups that have no runtime assigned >> @@ -1019,7 +1020,8 @@ 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("pid: %d, comm: %s, sched: RT throttling activated\n", >> + curr->pid, curr->comm); >> } else { >> /* >> * In case we did anyway, make it go away,
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