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From: Tejun Heo <tj@kernel.org>
To: Julia Lawall <julia.lawall@inria.fr>
Cc: torvalds@linux-foundation.org, mingo@redhat.com,
	peterz@infradead.org, juri.lelli@redhat.com,
	vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
	rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
	bristot@redhat.com, vschneid@redhat.com, ast@kernel.org,
	daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org,
	joshdon@google.com, brho@google.com, pjt@google.com,
	derkling@google.com, haoluo@google.com, dvernet@meta.com,
	dschatzberg@meta.com, dskarlat@cs.cmu.edu, riel@surriel.com,
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	kernel-team@meta.com
Subject: Re: [PATCH 14/31] sched_ext: Implement BPF extensible scheduler class
Date: Sun, 11 Dec 2022 20:08:07 -1000	[thread overview]
Message-ID: <Y5bFRym3iFSvcFMW@slm.duckdns.org> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2212120702560.2971@hadrien>

On Mon, Dec 12, 2022 at 07:03:56AM +0100, Julia Lawall wrote:
> > Yeah, scx_exampl_central needs to either set ops.dispatch_max_batch higher
> > according to number of CPUs or flush and exit the loop and retry when
> > scx_bpf_dispatch_nr_slots() reaches zero. Will update.
> 
> Since there could be any number of waking threads, maybe some kind of
> flush and retry solution would be better?

Yeah, cental is a bit unusual because it's scheudling for other CPUs too. In
most cases, this doesn't matter that much because whether to retry or not
can be determined by the kernel core code. There are a couple ways to go
about it. When slots run out, it can explicitly queue another scheduling
event on self, or use scx_bpf_consume() to flush the pending tasks. Either
should work but neither is particularly pretty. I'm trying to see whether I
can remove the static dispatch buffers altogether.

Thanks.

-- 
tejun

  reply	other threads:[~2022-12-12  6:08 UTC|newest]

Thread overview: 92+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-30  8:22 [PATCHSET RFC] sched: Implement BPF extensible scheduler class Tejun Heo
2022-11-30  8:22 ` [PATCH 01/31] rhashtable: Allow rhashtable to be used from irq-safe contexts Tejun Heo
2022-11-30 16:35   ` Linus Torvalds
2022-11-30 17:00     ` Tejun Heo
2022-12-06 21:36   ` [PATCH v2 " Tejun Heo
2022-12-09 10:50     ` patchwork-bot+netdevbpf
2022-11-30  8:22 ` [PATCH 02/31] cgroup: Implement cgroup_show_cftypes() Tejun Heo
2022-11-30  8:22 ` [PATCH 03/31] BPF: Add @prog to bpf_struct_ops->check_member() Tejun Heo
2022-11-30  8:22 ` [PATCH 04/31] sched: Allow sched_cgroup_fork() to fail and introduce sched_cancel_fork() Tejun Heo
2022-12-12 11:13   ` Peter Zijlstra
2022-12-12 18:03     ` Tejun Heo
2022-12-12 20:07       ` Peter Zijlstra
2022-12-12 20:12         ` Tejun Heo
2022-11-30  8:22 ` [PATCH 05/31] sched: Add sched_class->reweight_task() Tejun Heo
2022-12-12 11:22   ` Peter Zijlstra
2022-12-12 17:34     ` Tejun Heo
2022-12-12 20:11       ` Peter Zijlstra
2022-12-12 20:15         ` Tejun Heo
2022-11-30  8:22 ` [PATCH 06/31] sched: Add sched_class->switching_to() and expose check_class_changing/changed() Tejun Heo
2022-12-12 11:28   ` Peter Zijlstra
2022-12-12 17:59     ` Tejun Heo
2022-11-30  8:22 ` [PATCH 07/31] sched: Factor out cgroup weight conversion functions Tejun Heo
2022-11-30  8:22 ` [PATCH 08/31] sched: Expose css_tg() and __setscheduler_prio() in kernel/sched/sched.h Tejun Heo
2022-12-12 11:49   ` Peter Zijlstra
2022-12-12 17:47     ` Tejun Heo
2022-11-30  8:22 ` [PATCH 09/31] sched: Enumerate CPU cgroup file types Tejun Heo
2022-11-30  8:22 ` [PATCH 10/31] sched: Add @reason to sched_class->rq_{on|off}line() Tejun Heo
2022-12-12 11:57   ` Peter Zijlstra
2022-12-12 18:06     ` Tejun Heo
2022-11-30  8:22 ` [PATCH 11/31] sched: Add @reason to sched_move_task() Tejun Heo
2022-12-12 12:00   ` Peter Zijlstra
2022-12-12 17:54     ` Tejun Heo
2022-11-30  8:22 ` [PATCH 12/31] sched: Add normal_policy() Tejun Heo
2022-11-30  8:22 ` [PATCH 13/31] sched_ext: Add boilerplate for extensible scheduler class Tejun Heo
2022-11-30  8:22 ` [PATCH 14/31] sched_ext: Implement BPF " Tejun Heo
2022-12-02 17:08   ` Barret Rhoden
2022-12-02 18:01     ` Tejun Heo
2022-12-06 21:42       ` Tejun Heo
2022-12-06 21:44   ` Tejun Heo
2022-12-11 22:33   ` Julia Lawall
2022-12-12  2:15     ` Tejun Heo
2022-12-12  6:03       ` Julia Lawall
2022-12-12  6:08         ` Tejun Heo [this message]
2022-12-12 12:31   ` Peter Zijlstra
2022-12-12 20:03     ` Tejun Heo
2022-12-12 12:53   ` Peter Zijlstra
2022-12-12 21:33     ` Tejun Heo
2022-12-13 10:55       ` Peter Zijlstra
2022-12-13 18:12         ` Tejun Heo
2022-12-13 18:40           ` Rik van Riel
2022-12-13 23:20             ` Josh Don
2022-12-13 10:57       ` Peter Zijlstra
2022-12-13 17:32         ` Tejun Heo
2022-11-30  8:22 ` [PATCH 15/31] sched_ext: [TEMPORARY] Add temporary workaround kfunc helpers Tejun Heo
2022-11-30  8:22 ` [PATCH 16/31] sched_ext: Add scx_example_dummy and scx_example_qmap example schedulers Tejun Heo
2022-11-30  8:22 ` [PATCH 17/31] sched_ext: Add sysrq-S which disables the BPF scheduler Tejun Heo
2022-11-30  8:23 ` [PATCH 18/31] sched_ext: Implement runnable task stall watchdog Tejun Heo
2022-11-30  8:23 ` [PATCH 19/31] sched_ext: Allow BPF schedulers to disallow specific tasks from joining SCHED_EXT Tejun Heo
2022-11-30  8:23 ` [PATCH 20/31] sched_ext: Allow BPF schedulers to switch all eligible tasks into sched_ext Tejun Heo
2022-11-30  8:23 ` [PATCH 21/31] sched_ext: Implement scx_bpf_kick_cpu() and task preemption support Tejun Heo
2022-11-30  8:23 ` [PATCH 22/31] sched_ext: Add task state tracking operations Tejun Heo
2022-11-30  8:23 ` [PATCH 23/31] sched_ext: Implement tickless support Tejun Heo
2022-11-30  8:23 ` [PATCH 24/31] sched_ext: Add cgroup support Tejun Heo
2022-11-30  8:23 ` [PATCH 25/31] sched_ext: Implement SCX_KICK_WAIT Tejun Heo
2022-11-30  8:23 ` [PATCH 26/31] sched_ext: Implement sched_ext_ops.cpu_acquire/release() Tejun Heo
2022-11-30  8:23 ` [PATCH 27/31] sched_ext: Implement sched_ext_ops.cpu_online/offline() Tejun Heo
2022-11-30  8:23 ` [PATCH 28/31] sched_ext: Add Documentation/scheduler/sched-ext.rst Tejun Heo
2022-12-12  4:01   ` Bagas Sanjaya
2022-12-12  6:28     ` Tejun Heo
2022-12-12 13:07       ` Bagas Sanjaya
2022-12-12 17:30         ` Tejun Heo
2022-12-12 12:39   ` Peter Zijlstra
2022-12-12 17:16     ` Tejun Heo
2022-11-30  8:23 ` [PATCH 29/31] sched_ext: Add a basic, userland vruntime scheduler Tejun Heo
2022-11-30  8:23 ` [PATCH 30/31] BPF: [TEMPORARY] Nerf BTF scalar value check Tejun Heo
2022-11-30  8:23 ` [PATCH 31/31] sched_ext: Add a rust userspace hybrid example scheduler Tejun Heo
2022-12-12 14:03   ` Peter Zijlstra
2022-12-12 21:05     ` Peter Oskolkov
2022-12-13 11:02       ` Peter Zijlstra
2022-12-13 18:24         ` Peter Oskolkov
2022-12-12 22:00     ` Tejun Heo
2022-12-12 22:18     ` Josh Don
2022-12-13 11:30       ` Peter Zijlstra
2022-12-13 20:33         ` Tejun Heo
2022-12-14  2:00         ` Josh Don
2022-12-12  9:37 ` [PATCHSET RFC] sched: Implement BPF extensible scheduler class Peter Zijlstra
2022-12-12 17:27   ` Tejun Heo
2022-12-12 10:14 ` Peter Zijlstra
2022-12-14  2:11   ` Josh Don
2022-12-14  8:55     ` Peter Zijlstra
2022-12-14 22:23       ` Tejun Heo
2022-12-14 23:20         ` Barret Rhoden

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