Re: [PATCH v4 0/2] workqueue: Make WQ_UNBOUND the default behavior

[Tejun Heo]

Hello, Marco.

The following is a Claude-generated review.

On Thu, Oct 15, 2026 at 04:01:46PM +0200, Marco Crivellari wrote:
> Currently alloc_workqueue() make sure one among WQ_UNBOUND or WQ_PERCPU is
> present. This is enforced warning and setting WQ_PERCPU as default when
> alloc_workqueue() without WQ_PERCPU or WQ_UNBOUND.

- 1/2: The description gives the future removal of WQ_UNBOUND as the only
  reason. Can it lead with why unbound should be the default, as
  dadb3ebcf395 ("workqueue: WQ_PERCPU added to alloc_workqueue users")
  does?

  Moving the defaulting above the wq_size computation is the one subtle
  point. Maybe add a sentence on it to the description?

  The new comment says WQ_UNBOUND is final at that point, but the
  WQ_POWER_EFFICIENT block right below can still set it. The first two
  paragraphs restate the if/else. Maybe trim it to the ordering
  constraint against wq_size?

  unlikely() on the neither-flag branch now marks the path that's meant
  to become the default. Maybe drop it?

  The WQ_POWER_EFFICIENT comment in include/linux/workqueue.h says such
  workqueues are per-cpu by default. With this patch, one without
  WQ_PERCPU is unbound regardless of workqueue.power_efficient. All
  in-tree users pass WQ_PERCPU, so only the text needs updating.

  Typos: "achive", "alloc_users()" (alloc_workqueue() users), "ensure" ->
  "ensures", "neither flags are" -> "neither flag is".

- 2/2: The description says WQ_PERCPU is set for WQ_BH "regardless of
  what the caller passes", but WQ_BH | WQ_UNBOUND is rejected by the
  __WQ_BH_ALLOWS check.

  "the only permitted flags" dropped "additional", but WQ_BH itself is
  in __WQ_BH_ALLOWS too. Also, "workqueueus" typo.

  The new WQ_UNBOUND sentence sits after the "useful for the following
  cases" bullets and reads as one more case. Maybe move it to the top of
  the entry? Also, "Workqueue without" -> "Workqueues without".

  The Guidelines section still says "using a bound wq is usually
  beneficial", which now contradicts the default. Can that be updated
  too?

  Nit: doc patches in this tree usually use the "workqueue: doc:" prefix.

Thanks.

-- 
tejun