From: Tejun Heo <tj@kernel.org>
To: Andrea Righi <arighi@nvidia.com>
Cc: David Vernet <void@manifault.com>,
Changwoo Min <changwoo@igalia.com>,
sched-ext@lists.linux.dev, Emil Tsalapatis <emil@etsalapatis.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCHSET v5 sched_ext/for-7.3] sched_ext: Capability-based CPU delegation for sub-schedulers
Date: Mon, 13 Jul 2026 22:07:43 -1000 [thread overview]
Message-ID: <8839b71f9320a2fb81be66a2ca84cf86@kernel.org> (raw)
In-Reply-To: <alXg1Ux83csDVjKf@gpd4>
Hello, Andrea.
On Tue, Jul 14, 2026 at 09:10:13AM +0200, Andrea Righi wrote:
> I went through the series and tested the resulting kernel under virtme-ng. I
> couldn't trigger any crashes, lockups, or warnings, and I don't see any issues
> that should block applying this.
>
> As I mentioned, one possible follow-up optimization would be to introduce a
> "scx_has_sub_scheds" static key, indicating whether any sub-scheduler is
> attached. This could preserve the current fast paths for the common case of a
> single root-only scheduler, avoiding the small potential overhead of
> sub-scheduler-specific hierarchy walks and capability checks. And it could also
> enable additional optimizations in the future.
Yeah, gating the sub-sched-only paths behind a static key while no
sub-scheduler is attached is on the todo list. Will follow up with
incremental patches.
> For the series:
>
> Reviewed-by: Andrea Righi <arighi@nvidia.com>
Thanks a lot for the review and testing.
--
tejun
next prev parent reply other threads:[~2026-07-14 8:07 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-09 22:50 [PATCHSET v5 sched_ext/for-7.3] sched_ext: Capability-based CPU delegation for sub-schedulers Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 01/33] sched_ext: Assert per-task ops run on the task's owner Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 02/33] sched_ext: Make the kick machinery per-sched Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 03/33] sched_ext: Add ops.init_cids() to finalize the cid layout before init Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 04/33] sched_ext: Add CID sharding Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 05/33] sched_ext: Add shard boundaries to scx_bpf_cid_override() Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 06/33] sched_ext: Defer scx_sched kobj sysfs add into the enable workfns Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 07/33] sched_ext: Add per-shard scx_sched storage scaffolding Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 08/33] sched_ext: Add scx_cmask_ref for validated arena cmask access Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 09/33] sched_ext: Build the set_cmask scratch from trusted geometry Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 10/33] sched_ext: RCU-protect the sub-sched tree's children/sibling lists Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 11/33] sched_ext: Add scx_skip_subtree_pre() Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 12/33] sched_ext: Stop resolving a disabled scheduler's programs Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 13/33] sched_ext: Add per-shard cap delegation for sub-schedulers Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 14/33] sched_ext: Add coalescing sub_caps_updated() notifier " Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 15/33] sched_ext: Maintain per-cpu effective cap copies for single-read checks Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 16/33] sched_ext: Add sub_ecaps_updated() effective-cap change notifier Tejun Heo
2026-07-14 6:00 ` Andrea Righi
2026-07-14 8:07 ` Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 17/33] sched_ext: Generalize local-DSQ handling to rq-owned DSQs Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 18/33] sched_ext: Add reject DSQ for cap-rejected dispatches Tejun Heo
2026-07-14 6:49 ` Andrea Righi
2026-07-14 8:08 ` Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 19/33] sched_ext: Add SCX_ENQ_IGNORE_CAPS for in-place restore Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 20/33] sched_ext: Add the SCX_CAP_ENQ_IMMED cap Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 21/33] sched_ext: Assign a unique id to each scheduler instance Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 22/33] sched_ext: Route task slice writes through set_task_slice() Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 23/33] sched_ext: Track the cpu a task is runnable on Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 24/33] sched_ext: Tie cpu occupancy to SCX_CAP_BASE through the task slice Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 25/33] sched_ext: Add the SCX_CAP_ENQ cap Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 26/33] sched_ext: Gate kicks on SCX_CAP_BASE and preemption on SCX_CAP_PREEMPT Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 27/33] sched_ext: Authorize remote-move inserts against the placing scheduler Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 28/33] sched_ext: Route ops.update_idle() to sub-schedulers and re-notify owed scheds Tejun Heo
2026-07-14 6:18 ` Andrea Righi
2026-07-14 8:08 ` Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 29/33] sched_ext: Replay ecaps notifications suppressed by bypass Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 30/33] sched_ext: Add scx_bpf_sub_kill() to evict a child sub-scheduler Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 31/33] tools/sched_ext: Add three-mask cmask intersection iterator Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 32/33] tools/sched_ext: scx_qmap - Expand hierarchical sub-scheduling Tejun Heo
2026-07-09 22:50 ` [PATCH v5 sched_ext/for-7.3 33/33] tools/sched_ext: scx_qmap - Add sub-sched cap fault injection Tejun Heo
2026-07-14 7:10 ` [PATCHSET v5 sched_ext/for-7.3] sched_ext: Capability-based CPU delegation for sub-schedulers Andrea Righi
2026-07-14 8:07 ` Tejun Heo [this message]
2026-07-14 8:27 ` Tejun Heo
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