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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>,
	"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 v2 12/21] sched/debug: Show the deadline bandwidth of each runqueue
Date: Wed,  4 Nov 2026 16:11:58 -0500	[thread overview]
Message-ID: <20261104211207.1392343-13-mathieu.desnoyers@efficios.com> (raw)
In-Reply-To: <20261104211207.1392343-1-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 21:12 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-04 21:11 [PATCH v2 00/21] sched/deadline: bandwidth accounting fixes and selftests Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 01/21] sched: Reject SCHED_FLAG_KEEP_PARAMS before reserving deadline bandwidth Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 02/21] sched: Refuse SCHED_FLAG_KEEP_PARAMS that would change the policy Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 03/21] sched/deadline: Do not admit bandwidth for parameters that are kept Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 04/21] sched/deadline: Do not divide by zero active CPUs of a root domain Mathieu Desnoyers
2026-11-04 21:46   ` sashiko-bot
2026-11-04 21:11 ` [PATCH v2 05/21] sched/deadline: Do not BUG() on a deadline task with no active CPU allowed Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 06/21] sched/deadline: Do not lose a throttled task switched out and back Mathieu Desnoyers
2026-11-04 22:09   ` sashiko-bot
2026-11-04 21:11 ` [PATCH v2 07/21] sched/deadline: Do not release a departing sleeper's bandwidth twice Mathieu Desnoyers
2026-11-04 22:15   ` sashiko-bot
2026-11-04 21:11 ` [PATCH v2 08/21] selftests/sched: Add a test of SCHED_DEADLINE policy round trips Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 09/21] sched/deadline: Keep departing bandwidth across a root domain rebuild Mathieu Desnoyers
2026-11-04 22:44   ` sashiko-bot
2026-11-04 21:11 ` [PATCH v2 10/21] selftests/sched: Test SCHED_DEADLINE " Mathieu Desnoyers
2026-11-04 21:11 ` [PATCH v2 11/21] sched/deadline: Do not take a waking task's bandwidth off a runqueue it left Mathieu Desnoyers
2026-11-04 21:11 ` Mathieu Desnoyers [this message]
2026-11-04 21:11 ` [PATCH v2 13/21] sched/deadline: Rebuild the root domains' accounting without cpusets too Mathieu Desnoyers
2026-11-04 23:18   ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 14/21] selftests/sched: Add a test of SCHED_DEADLINE bandwidth accounting Mathieu Desnoyers
2026-11-04 21:12 ` [PATCH v2 15/21] sched/deadline: Record the root domain holding a task's bandwidth Mathieu Desnoyers
2026-11-04 23:31   ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 16/21] sched/deadline: Move a task's bandwidth only where room was made Mathieu Desnoyers
2026-11-04 21:12 ` [PATCH v2 17/21] cgroup/cpuset: Give back the bandwidth an attach did not move Mathieu Desnoyers
2026-11-04 23:56   ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 18/21] sched/deadline: Credit a rebuild to a CPU that can hold the bandwidth Mathieu Desnoyers
2026-11-05  0:18   ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 19/21] sched: Clear cpuset_locked where the policy check retries Mathieu Desnoyers
2026-11-04 21:12 ` [PATCH v2 20/21] sched/deadline: Cancel the replenishment timer with the parameters Mathieu Desnoyers
2026-11-05  0:25   ` sashiko-bot
2026-11-04 21:12 ` [PATCH v2 21/21] sched/deadline: Count the bandwidth a boosted task is given Mathieu Desnoyers
2026-11-05  0:36   ` sashiko-bot

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