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Thu, 12 Nov 2026 02:36:08 -0800 (PST) X-Received: by 2002:a05:600c:8b57:b0:4ba:4395:560f with SMTP id 5b1f17b1804b1-4bb4e283efamr44874665e9.8.1794479768472; Thu, 12 Nov 2026 02:36:08 -0800 (PST) Received: from jlelli-thinkpadt14gen4.remote.csb ([151.29.158.90]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4bb4e27a8b0sm60917155e9.15.2026.11.12.02.36.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Nov 2026 02:36:06 -0800 (PST) Date: Thu, 12 Nov 2026 11:36:04 +0100 From: Juri Lelli To: Mathieu Desnoyers Cc: peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, tglx@kernel.org, will@kernel.org, boqun@kernel.org, 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: Re: [PATCH v5 26/29] sched/debug: Show the deadline bandwidth of each runqueue Message-ID: References: <20261108185406.1549770-1-mathieu.desnoyers@efficios.com> <20261108185406.1549770-27-mathieu.desnoyers@efficios.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261108185406.1549770-27-mathieu.desnoyers@efficios.com> Hello, On 08/11/26 13:54, Mathieu Desnoyers wrote: > For each CPU, sched_debug prints the deadline bandwidth of its root > domain. It does not print the two sums of its runqueue. this_bw is the > bandwidth of the deadline tasks assigned to the CPU. running_bw is the > part of it that belongs to active tasks. > > GRUB reclaiming depends on both sums. grub_reclaim() takes this_bw - > running_bw as the inactive bandwidth of the CPU. The more inactive > bandwidth, the slower a reclaiming task uses up its runtime. > > The kernel warns when a sum wraps around, and when running_bw exceeds > this_bw. Bandwidth left behind in this_bw triggers no warning. > > Print both sums. The deadline_bw_test selftest added later in this > series reads this_bw in its params_waking and random_mix cases. It > checks that this_bw is back to its first value once their tasks are > gone. > > Signed-off-by: Mathieu Desnoyers > --- > kernel/sched/debug.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c > index e0d6cd3bd607..3dbe1d7d2d77 100644 > --- a/kernel/sched/debug.c > +++ b/kernel/sched/debug.c > @@ -1174,6 +1174,8 @@ 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); OK, but we will still not printing additional useful information like extra_bw, etc. Not sure if you are aware of tools/sched/dl_bw_dump.py drgn script; maybe that is already useful for the needed additional debugging information? Thanks, Juri