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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Juri Lelli <juri.lelli@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>
Cc: linux-kernel@vger.kernel.org,
	"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
	"Dietmar Eggemann" <dietmar.eggemann@arm.com>,
	"Steven Rostedt" <rostedt@goodmis.org>,
	"Ben Segall" <bsegall@google.com>, "Mel Gorman" <mgorman@suse.de>,
	"Valentin Schneider" <vschneid@redhat.com>,
	"K Prateek Nayak" <kprateek.nayak@amd.com>,
	"Luca Abeni" <luca.abeni@santannapisa.it>,
	"Claudio Scordino" <claudio@evidence.eu.com>,
	"Mathieu Poirier" <mathieu.poirier@linaro.org>,
	"Waiman Long" <longman@redhat.com>,
	"Ridong Chen" <ridong.chen@linux.dev>,
	"Tejun Heo" <tj@kernel.org>,
	"Johannes Weiner" <hannes@cmpxchg.org>,
	"Michal Koutný" <mkoutny@suse.com>,
	"Shuah Khan" <shuah@kernel.org>,
	"Sebastian Andrzej Siewior" <bigeasy@linutronix.de>,
	"Clark Williams" <clrkwllms@kernel.org>,
	cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org,
	linux-rt-devel@lists.linux.dev
Subject: [PATCH 10/12] sched/debug: Show the deadline bandwidth of each runqueue
Date: Wed,  4 Nov 2026 10:10:31 -0500	[thread overview]
Message-ID: <f67fc6f8ee934d03960de70fe5404072ea59e83f.1793804635.git.mathieu.desnoyers@efficios.com> (raw)
In-Reply-To: <cover.1793804635.git.mathieu.desnoyers@efficios.com>

sched_debug prints the bandwidth each root domain has handed out
(dl_bw->total_bw), and nothing of the two sums each runqueue keeps:
this_bw, the bandwidth of every deadline task of that CPU, and
running_bw, the part of it whose tasks are active. GRUB drains the
runtime of a reclaiming task at the rate the two give, the bandwidth of
its CPU that is reserved and active (grub_reclaim(): max_bw - (this_bw -
running_bw) - extra_bw): the less of its CPU is active, the slower its
runtime drains, and the longer it runs on.

Both sums have invariants a test can check, which the kernel itself
warns about when they break: neither may wrap, and running_bw never
exceeds this_bw. Print them.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
 kernel/sched/debug.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index e6a3b516c703..8a726817baa0 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1166,6 +1166,8 @@ void print_dl_rq(struct seq_file *m, int cpu, struct dl_rq *dl_rq)
 	SEQ_printf(m, "  .%-30s: %lu\n", #x, (unsigned long)(dl_rq->x))
 
 	PU(dl_nr_running);
+	PU(running_bw);
+	PU(this_bw);
 	dl_bw = &cpu_rq(cpu)->rd->dl_bw;
 	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);
-- 
2.47.3


  parent reply	other threads:[~2026-11-04 15:12 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-04 15:10 [PATCH 00/12] sched/deadline: bandwidth accounting fixes and selftests Mathieu Desnoyers
2026-11-04 15:10 ` [PATCH 01/12] sched: Reject SCHED_FLAG_KEEP_PARAMS before reserving deadline bandwidth Mathieu Desnoyers
2026-11-04 15:30   ` sashiko-bot
2026-11-04 15:52     ` Mathieu Desnoyers
2026-11-04 15:10 ` [PATCH 02/12] sched/deadline: Do not divide by zero active CPUs of a root domain Mathieu Desnoyers
2026-11-04 15:10 ` [PATCH 03/12] sched/deadline: Do not BUG() on a deadline task with no active CPU allowed Mathieu Desnoyers
2026-11-04 15:39   ` sashiko-bot
2026-11-04 15:10 ` [PATCH 04/12] sched/deadline: Do not lose a throttled task switched out and back Mathieu Desnoyers
2026-11-04 15:42   ` sashiko-bot
2026-11-04 15:10 ` [PATCH 05/12] sched/deadline: Do not release a departing sleeper's bandwidth twice Mathieu Desnoyers
2026-11-04 15:33   ` sashiko-bot
2026-11-04 15:10 ` [PATCH 06/12] selftests/sched: Add a test of SCHED_DEADLINE policy round trips Mathieu Desnoyers
2026-11-04 15:10 ` [PATCH 07/12] sched/deadline: Keep departing bandwidth across a root domain rebuild Mathieu Desnoyers
2026-11-04 15:47   ` sashiko-bot
2026-11-04 15:10 ` [PATCH 08/12] selftests/sched: Test SCHED_DEADLINE " Mathieu Desnoyers
2026-11-04 15:10 ` [PATCH 09/12] sched/deadline: Do not take a waking task's bandwidth off a runqueue it left Mathieu Desnoyers
2026-11-04 15:45   ` sashiko-bot
2026-11-04 15:10 ` Mathieu Desnoyers [this message]
2026-11-04 15:10 ` [PATCH 11/12] sched/deadline: Rebuild the root domains' accounting without cpusets too Mathieu Desnoyers
2026-11-04 15:45   ` sashiko-bot
2026-11-04 15:10 ` [PATCH 12/12] selftests/sched: Add a test of SCHED_DEADLINE bandwidth accounting Mathieu Desnoyers
2026-11-04 15:52   ` sashiko-bot
2026-11-04 20:24 ` [PATCH 00/12] sched/deadline: bandwidth accounting fixes and selftests Mathieu Desnoyers

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