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Groups > linux.kernel > #1325698
| From | Steven Rostedt <rostedt@goodmis.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [RFC][PATCH 3/3 v2] sched: Add bandwidth ratio to /proc/sched_debug |
| Date | 2016-02-03 18:10 +0100 |
| Message-ID | <qY96j-4P4-33@gated-at.bofh.it> (permalink) |
| References | <qY96j-4P4-17@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Playing with SCHED_DEADLINE and cpusets, I found that I was unable to create
new SCHED_DEADLINE tasks, with the error of EBUSY as if the bandwidth was
already used up. I then realized there wa no way to see what bandwidth is
used by the runqueues to debug the issue.
By adding the dl_bw->bw and dl_bw->total_bw to the output of the deadline
info in /proc/sched_debug, this allows us to see what bandwidth has been
reserved and where a problem may exist.
For example, before the issue we see the ratio of the bandwidth:
# cat /proc/sys/kernel/sched_rt_runtime_us
950000
# cat /proc/sys/kernel/sched_rt_period_us
1000000
# grep dl /proc/sched_debug
dl_rq[0]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[1]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[2]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[3]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[4]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[5]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[6]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
dl_rq[7]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 0
Note: (950000 / 1000000) << 20 == 996147
After I played with cpusets and hit the issue, the result is now:
# grep dl /proc/sched_debug
dl_rq[0]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
dl_rq[1]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 104857
dl_rq[2]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 104857
dl_rq[3]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : 104857
dl_rq[4]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
dl_rq[5]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
dl_rq[6]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
dl_rq[7]:
.dl_nr_running : 0
.dl_bw->bw : 996147
.dl_bw->total_bw : -104857
This shows that there is definitely a problem as we should never have a
negative total bandwidth.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/sched/debug.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index a5625e793d15..a1f161a7500e 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -562,8 +562,17 @@ void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq)
void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq)
{
+ struct dl_bw *dl_bw;
+
SEQ_printf(m, "\ndl_rq[%d]:\n", cpu);
SEQ_printf(m, " .%-30s: %ld\n", "dl_nr_running", dl_rq->dl_nr_running);
+#ifdef CONFIG_SMP
+ dl_bw = &cpu_rq(cpu)->rd->dl_bw;
+#else
+ dl_bw = &dl_rq->dl_bw;
+#endif
+ SEQ_printf(m, " .%-30s: %lld\n", "dl_bw->bw", dl_bw->bw);
+ SEQ_printf(m, " .%-30s: %lld\n", "dl_bw->total_bw", dl_bw->total_bw);
}
extern __read_mostly int sched_clock_running;
--
2.6.4
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[RFC][PATCH 0/3 v2] sched: Display deadline bandwidth and other SCHED_DEBUG clean up Steven Rostedt <rostedt@goodmis.org> - 2016-02-03 18:10 +0100
[RFC][PATCH 1/3 v2] sched: Move sched_feature file setup into debug.c Steven Rostedt <rostedt@goodmis.org> - 2016-02-03 18:10 +0100
[RFC][PATCH 2/3 v2] sched: Move sched_domain_sysctl to debug.c Steven Rostedt <rostedt@goodmis.org> - 2016-02-03 18:10 +0100
[RFC][PATCH 3/3 v2] sched: Add bandwidth ratio to /proc/sched_debug Steven Rostedt <rostedt@goodmis.org> - 2016-02-03 18:10 +0100
Re: [RFC][PATCH 3/3 v2] sched: Add bandwidth ratio to /proc/sched_debug Juri Lelli <juri.lelli@arm.com> - 2016-02-03 19:00 +0100
Re: [RFC][PATCH 3/3 v2] sched: Add bandwidth ratio to /proc/sched_debug Steven Rostedt <rostedt@goodmis.org> - 2016-02-03 19:20 +0100
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