From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Juri Lelli <juri.lelli@redhat.com>
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,
stable@vger.kernel.org
Subject: Re: [PATCH v5 05/29] sched/deadline: Do not divide by zero active CPUs of a root domain
Date: Mon, 9 Nov 2026 09:57:33 -0500 [thread overview]
Message-ID: <3e6677a8-b972-4081-a080-e925fe1df3b0@efficios.com> (raw)
In-Reply-To: <avHY7oNeuvjsLT4I@jlelli-thinkpadt14gen4.remote.csb>
On 2026-11-09 09:30, Juri Lelli wrote:
[...]
> This 2nd hunk complements and tightens 4043f54984161 ("sched/deadline:
> Reject debugfs dl_server writes for offline CPUs") which has Fixes:
> d741f297bcea ("sched/fair: Fair server interface"). Do we need both
> fixes (if that is allowed) or maybe we need to split this change in two
> (as this second part won't apply to old kernels w/o dl-servers)?
Good point. I will split it in two in the next version:
- __dl_sub() and __dl_add() skip the division when the root domain has
no active CPU. Fixes: daec57983670. This alone removes the divide
error, on the debugfs path too.
- The debugfs write is refused while the runqueue is offline. Fixes:
4043f5498416, which it completes for the hotplug windows. It only
applies where that commit is.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com
next prev parent reply other threads:[~2026-11-09 14:57 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-08 18:53 [PATCH v5 00/29] sched/deadline: bandwidth accounting fixes and selftests Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 01/29] sched: Fix cpuset_mutex double unlock in __sched_setscheduler() Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 02/29] sched: Refuse SCHED_FLAG_KEEP_PARAMS that would change the policy or the class Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 03/29] sched/deadline: Do not admit bandwidth for parameters that are kept Mathieu Desnoyers
2026-11-09 12:42 ` Juri Lelli
2026-11-09 13:16 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 04/29] sched: Let a task boosted by a deadline waiter change its policy Mathieu Desnoyers
2026-11-09 13:38 ` Juri Lelli
2026-11-08 18:53 ` [PATCH v5 05/29] sched/deadline: Do not divide by zero active CPUs of a root domain Mathieu Desnoyers
2026-11-09 14:30 ` Juri Lelli
2026-11-09 14:57 ` Mathieu Desnoyers [this message]
2026-11-09 15:09 ` Juri Lelli
2026-11-09 15:22 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 06/29] sched: Take cpuset_mutex for a deadline policy change only with pi Mathieu Desnoyers
2026-11-09 15:06 ` Juri Lelli
2026-11-09 15:22 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 07/29] sched/deadline: Do not lose a throttled task switched out and back Mathieu Desnoyers
2026-11-09 16:05 ` Juri Lelli
2026-11-09 16:29 ` Mathieu Desnoyers
2026-11-09 18:55 ` Mathieu Desnoyers
2026-11-09 18:56 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 08/29] sched/deadline: Take a deadline boost from the waiter's rt_mutex node Mathieu Desnoyers
2026-11-10 11:14 ` Juri Lelli
2026-11-10 13:48 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 09/29] sched/deadline: Reset the deadline and the runtime with the parameters Mathieu Desnoyers
2026-11-10 13:18 ` Juri Lelli
2026-11-10 13:41 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 10/29] sched/deadline: Reset the donor's runtime at a deboost in the class Mathieu Desnoyers
2026-11-08 19:17 ` sashiko-bot
2026-11-09 2:56 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 11/29] sched/deadline: Release the bandwidth of a task that leaves the class asleep Mathieu Desnoyers
2026-11-10 19:47 ` Juri Lelli
2026-11-10 20:26 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 12/29] sched/deadline: Reject SCHED_DEADLINE on exited tasks Mathieu Desnoyers
2026-11-11 6:55 ` Juri Lelli
2026-11-08 18:53 ` [PATCH v5 13/29] sched/deadline: Keep departing bandwidth across a root domain rebuild Mathieu Desnoyers
2026-11-11 12:59 ` Juri Lelli
2026-11-11 15:35 ` Mathieu Desnoyers
2026-11-11 16:19 ` Peter Zijlstra
2026-11-11 19:19 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 14/29] sched/deadline: Fix this_bw when a task is changed during a remote wakeup Mathieu Desnoyers
2026-11-11 13:49 ` Juri Lelli
2026-11-08 18:53 ` [PATCH v5 15/29] sched/deadline: Rebuild the root domains' accounting from the task list Mathieu Desnoyers
2026-11-11 14:24 ` Juri Lelli
2026-11-08 18:53 ` [PATCH v5 16/29] sched/deadline: Record the root domain holding a task's bandwidth Mathieu Desnoyers
2026-11-11 15:54 ` Juri Lelli
2026-11-08 18:53 ` [PATCH v5 17/29] sched/deadline: Leave a dying task out of a rebuild of the accounting Mathieu Desnoyers
2026-11-12 6:40 ` Juri Lelli
2026-11-08 18:53 ` [PATCH v5 18/29] sched/deadline: Move a task's bandwidth only where room was made Mathieu Desnoyers
2026-11-08 19:30 ` sashiko-bot
2026-11-09 2:57 ` Mathieu Desnoyers
2026-11-12 7:03 ` Juri Lelli
2026-11-08 18:53 ` [PATCH v5 19/29] cgroup/cpuset: Wait for an attach before rebuilding the sched domains Mathieu Desnoyers
2026-11-12 7:50 ` Juri Lelli
2026-11-08 18:53 ` [PATCH v5 20/29] cgroup/cpuset: Give back the bandwidth an attach did not move Mathieu Desnoyers
2026-11-12 9:19 ` Juri Lelli
2026-11-08 18:53 ` [PATCH v5 21/29] cgroup/cpuset: Reserve the bandwidth in the root domain a task moves to Mathieu Desnoyers
2026-11-08 19:32 ` sashiko-bot
2026-11-09 2:57 ` Mathieu Desnoyers
2026-11-08 18:53 ` [PATCH v5 22/29] sched/deadline: Make a rebuild use the CPU recorded with a task's bandwidth Mathieu Desnoyers
2026-11-08 19:25 ` sashiko-bot
2026-11-09 2:58 ` Mathieu Desnoyers
2026-11-08 18:54 ` [PATCH v5 23/29] sched/deadline: Move a task's bandwidth when it must leave its CPU Mathieu Desnoyers
2026-11-08 19:41 ` sashiko-bot
2026-11-09 2:58 ` Mathieu Desnoyers
2026-11-08 18:54 ` [PATCH v5 24/29] sched/deadline: Cancel the replenishment timer with the parameters Mathieu Desnoyers
2026-11-12 9:37 ` Juri Lelli
2026-11-08 18:54 ` [PATCH v5 25/29] sched/deadline: Count the bandwidth a boosted task is given Mathieu Desnoyers
2026-11-12 10:29 ` Juri Lelli
2026-11-08 18:54 ` [PATCH v5 26/29] sched/debug: Show the deadline bandwidth of each runqueue Mathieu Desnoyers
2026-11-12 10:36 ` Juri Lelli
2026-11-08 18:54 ` [PATCH v5 27/29] selftests/sched: Add a test of SCHED_DEADLINE policy round trips Mathieu Desnoyers
2026-11-08 18:54 ` [PATCH v5 28/29] selftests/sched: Test SCHED_DEADLINE bandwidth across a root domain rebuild Mathieu Desnoyers
2026-11-08 18:54 ` [PATCH v5 29/29] selftests/sched: Add a test of SCHED_DEADLINE bandwidth accounting Mathieu Desnoyers
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