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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2016-02-22 16:26:52 -0500
committerIngo Molnar <mingo@kernel.org>2016-02-29 09:53:07 +0100
commitef477183d06b0aa41c9e7c02cf5bfec41536e2c4 (patch)
tree5712df260ff653b50d11424efc55bb7f1f45eb6d /kernel/sched/debug.c
parent3866e845ed522258c77da2eaa9f849ef55206ca2 (diff)
downloadlinux-ef477183d06b0aa41c9e7c02cf5bfec41536e2c4.tar.bz2
sched/debug: Add deadline scheduler bandwidth ratio to /proc/sched_debug
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> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Clark Williams <williams@redhat.com> Cc: Juri Lelli <juri.lelli@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20160222212825.756849091@goodmis.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/debug.c')
-rw-r--r--kernel/sched/debug.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 313c65fe2087..4fbc3bd5ff60 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -566,8 +566,17 @@ 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;