From: Thomas Gleixner <tglx@linutronix.de>
To: Phil Auld <pauld@redhat.com>, Waiman Long <llong@redhat.com>
Cc: Frederic Weisbecker <frederic@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Marco Crivellari <marco.crivellari@suse.com>,
Michal Hocko <mhocko@suse.com>,
Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>
Subject: Re: [PATCH 02/27] sched/isolation: Introduce housekeeping per-cpu rwsem
Date: Mon, 30 Jun 2025 14:59:00 +0200 [thread overview]
Message-ID: <878ql9o06j.ffs@tglx> (raw)
In-Reply-To: <20250627004851.GB222768@pauld.westford.csb>
On Thu, Jun 26 2025 at 20:48, Phil Auld wrote:
> On Thu, Jun 26, 2025 at 08:11:54PM -0400 Waiman Long wrote:
>> > My understanding is that it's the stop machine issue. If you have a way
>> > around that then great!
>>
>> My current thinking is to just run a selected set of CPUHP teardown and
>> startup methods relevant to housekeeping cpumasks usage without calling the
>> full set from CPUHP_ONLINE to CPUHP_OFFLINE. I don't know if it is possible
>> or not or how much additional changes will be needed to make that possible.
>> That will skip the CPUHP_TEARDOWN_CPU teardown method that is likely the
>> cause of most the latency spike experienced by other CPUs.
>>
>
> Yes, CPUHP_TEARDOWN_CPU is the source of the stop_machine I believe.
Correct.
> It'll be interesting to see if you can safely use the cpuhp machinery
> selectively like that :)
It is supposed to work that way and you can exercise it from userspace
via sysfs already. If it fails, then there are bugs in hotplug callbacks
or ordering or ..., which need to be fixed anyway :)
Thanks,
tglx
next prev parent reply other threads:[~2025-06-30 12:59 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-20 15:22 [PATCH 00/27] cpuset/isolation: Honour kthreads preferred affinity Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 01/27] sched/isolation: Remove housekeeping static key Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 02/27] sched/isolation: Introduce housekeeping per-cpu rwsem Frederic Weisbecker
2025-06-23 17:34 ` Waiman Long
2025-06-23 17:39 ` Tejun Heo
2025-06-23 17:57 ` Waiman Long
2025-06-23 18:03 ` Tejun Heo
2025-06-25 14:30 ` Frederic Weisbecker
2025-06-25 12:18 ` Phil Auld
2025-06-25 14:34 ` Frederic Weisbecker
2025-06-25 15:50 ` Phil Auld
2025-06-27 0:11 ` Waiman Long
2025-06-27 0:48 ` Phil Auld
2025-06-30 12:59 ` Thomas Gleixner [this message]
2025-06-25 14:18 ` Frederic Weisbecker
2025-06-26 23:58 ` Waiman Long
2025-06-20 15:22 ` [PATCH 03/27] PCI: Protect against concurrent change of housekeeping cpumask Frederic Weisbecker
2025-06-20 16:17 ` Bjorn Helgaas
2025-06-26 14:51 ` Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 04/27] cpu: Protect against concurrent isolated cpuset change Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 05/27] memcg: Prepare to protect " Frederic Weisbecker
2025-06-20 19:19 ` Shakeel Butt
2025-06-20 15:22 ` [PATCH 06/27] mm: vmstat: " Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 07/27] sched/isolation: Save boot defined domain flags Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 08/27] cpuset: Convert boot_hk_cpus to use HK_TYPE_DOMAIN_BOOT Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 09/27] driver core: cpu: Convert /sys/devices/system/cpu/isolated " Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 10/27] net: Keep ignoring isolated cpuset change Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 11/27] block: Protect against concurrent " Frederic Weisbecker
2025-06-20 15:59 ` Bart Van Assche
2025-06-26 15:03 ` Frederic Weisbecker
2025-06-23 5:46 ` Christoph Hellwig
2025-06-26 15:33 ` Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 12/27] cpu: Provide lockdep check for CPU hotplug lock write-held Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 13/27] cpuset: Provide lockdep check for cpuset lock held Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 14/27] sched/isolation: Convert housekeeping cpumasks to rcu pointers Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 15/27] cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 16/27] sched/isolation: Flush memcg workqueues on cpuset isolated partition change Frederic Weisbecker
2025-06-20 19:30 ` Shakeel Butt
2025-06-20 15:22 ` [PATCH 17/27] sched/isolation: Flush vmstat " Frederic Weisbecker
2025-06-20 15:22 ` [PATCH 18/27] cpuset: Propagate cpuset isolation update to workqueue through housekeeping Frederic Weisbecker
2025-06-20 15:23 ` [PATCH 19/27] cpuset: Remove cpuset_cpu_is_isolated() Frederic Weisbecker
2025-06-20 15:23 ` [PATCH 20/27] sched/isolation: Remove HK_TYPE_TICK test from cpu_is_isolated() Frederic Weisbecker
2025-06-20 15:23 ` [PATCH 21/27] kthread: Refine naming of affinity related fields Frederic Weisbecker
2025-06-20 15:23 ` [PATCH 22/27] kthread: Include unbound kthreads in the managed affinity list Frederic Weisbecker
2025-06-20 15:23 ` [PATCH 23/27] kthread: Include kthreadd to " Frederic Weisbecker
2025-06-20 15:23 ` [PATCH 24/27] kthread: Rely on HK_TYPE_DOMAIN for preferred affinity management Frederic Weisbecker
2025-06-20 15:23 ` [PATCH 25/27] sched: Switch the fallback task allowed cpumask to HK_TYPE_DOMAIN Frederic Weisbecker
2025-06-20 15:23 ` [PATCH 26/27] kthread: Honour kthreads preferred affinity after cpuset changes Frederic Weisbecker
2025-06-20 15:23 ` [PATCH 27/27] kthread: Comment on the purpose and placement of kthread_affine_node() call Frederic Weisbecker
2025-06-20 16:08 ` [PATCH 00/27] cpuset/isolation: Honour kthreads preferred affinity Bjorn Helgaas
2025-06-26 14:57 ` Frederic Weisbecker
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