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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: juri.lelli@redhat.com, peterz@infradead.org, mingo@redhat.com,
	vincent.guittot@linaro.org
Cc: linux-kernel@vger.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	dietmar.eggemann@arm.com, rostedt@goodmis.org,
	bsegall@google.com, mgorman@suse.de, vschneid@redhat.com,
	kprateek.nayak@amd.com, luca.abeni@santannapisa.it,
	mathieu.poirier@linaro.org, longman@redhat.com,
	ridong.chen@linux.dev, tj@kernel.org, hannes@cmpxchg.org,
	mkoutny@suse.com, shuah@kernel.org, bigeasy@linutronix.de,
	clrkwllms@kernel.org, parri.andrea@gmail.com,
	m.szyprowski@samsung.com, kayracizmeci@gmail.com,
	weihengqiuu@gmail.com, cgroups@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-rt-devel@lists.linux.dev
Subject: [PATCH v3 21/24] sched/debug: Show the deadline bandwidth of each runqueue
Date: Thu,  5 Nov 2026 14:33:56 -0500	[thread overview]
Message-ID: <20261105193359.1450487-22-mathieu.desnoyers@efficios.com> (raw)
In-Reply-To: <20261105193359.1450487-1-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 a4ae092e0a68..c8a2cf18fdd1 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -1171,6 +1171,8 @@ 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:[~2026-11-05 19:34 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-05 19:33 [PATCH v3 00/24] sched/deadline: bandwidth accounting fixes and selftests Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 01/24] sched: Fix cpuset_mutex double unlock in __sched_setscheduler() Mathieu Desnoyers
2026-11-05 19:51   ` Kayra Cizmeci
2026-11-05 19:54     ` Mathieu Desnoyers
2026-11-05 19:59       ` Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 02/24] sched: Refuse SCHED_FLAG_KEEP_PARAMS that would change the policy or the class Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 03/24] sched/deadline: Do not admit bandwidth for parameters that are kept Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 04/24] sched/deadline: Do not divide by zero active CPUs of a root domain Mathieu Desnoyers
2026-11-05 19:59   ` sashiko-bot
2026-11-05 19:33 ` [PATCH v3 05/24] sched: Take cpuset_mutex for a deadline policy change only with pi Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 06/24] sched/deadline: Do not lose a throttled task switched out and back Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 07/24] sched/deadline: Reset the deadline and the runtime with the parameters Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 08/24] sched/deadline: Release the bandwidth of a task that leaves the class asleep Mathieu Desnoyers
2026-11-05 20:10   ` sashiko-bot
2026-11-05 19:33 ` [PATCH v3 09/24] sched/deadline: Reject SCHED_DEADLINE on exited tasks Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 10/24] sched/deadline: Keep departing bandwidth across a root domain rebuild Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 11/24] sched/deadline: Do not take a waking task's bandwidth off a runqueue it left Mathieu Desnoyers
2026-11-05 20:35   ` sashiko-bot
2026-11-05 19:33 ` [PATCH v3 12/24] sched/deadline: Rebuild the root domains' accounting without cpusets too Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 13/24] sched/deadline: Leave a dying task out of a rebuild of the accounting Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 14/24] sched/deadline: Record the root domain holding a task's bandwidth Mathieu Desnoyers
2026-11-05 20:50   ` sashiko-bot
2026-11-05 19:33 ` [PATCH v3 15/24] sched/deadline: Move a task's bandwidth only where room was made Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 16/24] cgroup/cpuset: Wait for an attach before rebuilding the sched domains Mathieu Desnoyers
2026-11-05 20:36   ` sashiko-bot
2026-11-05 19:33 ` [PATCH v3 17/24] cgroup/cpuset: Give back the bandwidth an attach did not move Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 18/24] sched/deadline: Credit a rebuild to the CPU recorded with the task's bandwidth Mathieu Desnoyers
2026-11-05 20:58   ` sashiko-bot
2026-11-05 19:33 ` [PATCH v3 19/24] sched/deadline: Cancel the replenishment timer with the parameters Mathieu Desnoyers
2026-11-05 21:05   ` sashiko-bot
2026-11-05 19:33 ` [PATCH v3 20/24] sched/deadline: Count the bandwidth a boosted task is given Mathieu Desnoyers
2026-11-05 21:13   ` sashiko-bot
2026-11-05 19:33 ` Mathieu Desnoyers [this message]
2026-11-05 19:33 ` [PATCH v3 22/24] selftests/sched: Add a test of SCHED_DEADLINE policy round trips Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 23/24] selftests/sched: Test SCHED_DEADLINE bandwidth across a root domain rebuild Mathieu Desnoyers
2026-11-05 19:33 ` [PATCH v3 24/24] selftests/sched: Add a test of SCHED_DEADLINE bandwidth accounting Mathieu Desnoyers
2026-11-05 21:17   ` sashiko-bot
2026-11-05 21:20 ` [PATCH v3 00/24] sched/deadline: bandwidth accounting fixes and selftests Mathieu Desnoyers

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