linux-kernel - Re: [PATCH v2 1/2] wifi: rtlwifi: add WQ_UNBOUND to alloc

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Message-ID: <daecde81-29d9-43e9-89d4-f7aa2010db62@RTKEXHMBS04.realtek.com.tw>
Date: Fri, 21 Nov 2025 11:49:05 +0800
From: Ping-Ke Shih <pkshih@...ltek.com>
To: Marco Crivellari <marco.crivellari@...e.com>,
        <linux-kernel@...r.kernel.org>, <linux-wireless@...r.kernel.org>
CC: Tejun Heo <tj@...nel.org>, Lai Jiangshan <jiangshanlai@...il.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Sebastian Andrzej Siewior
	<bigeasy@...utronix.de>,
        Marco Crivellari <marco.crivellari@...e.com>,
        Michal
 Hocko <mhocko@...e.com>, Ping-Ke Shih <pkshih@...ltek.com>
Subject: Re: [PATCH v2 1/2] wifi: rtlwifi: add WQ_UNBOUND to alloc_workqueue users

Marco Crivellari <marco.crivellari@...e.com> wrote:

> Currently if a user enqueues a work item using schedule_delayed_work() the
> used wq is "system_wq" (per-cpu wq) while queue_delayed_work() use
> WORK_CPU_UNBOUND (used when a cpu is not specified). The same applies to
> schedule_work() that is using system_wq and queue_work(), that makes use
> again of WORK_CPU_UNBOUND.
> 
> This lack of consistency cannot be addressed without refactoring the API.
> For more details see the Link tag below.
> 
> alloc_workqueue() treats all queues as per-CPU by default, while unbound
> workqueues must opt-in via WQ_UNBOUND.
> 
> This default is suboptimal: most workloads benefit from unbound queues,
> allowing the scheduler to place worker threads where they’re needed and
> reducing noise when CPUs are isolated.
> 
> This continues the effort to refactor workqueue APIs, which began with
> the introduction of new workqueues and a new alloc_workqueue flag in:
> 
> commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
> commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
> 
> This change adds the WQ_UNBOUND flag to explicitly request
> alloc_workqueue() to be unbound, because this specific workload has no
> benefit being per-cpu.
> 
> With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
> any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
> must now use WQ_PERCPU.
> 
> Once migration is complete, WQ_UNBOUND can be removed and unbound will
> become the implicit default.
> 
> Suggested-by: Tejun Heo <tj@...nel.org>
> Signed-off-by: Marco Crivellari <marco.crivellari@...e.com>
> Link: https://lore.kernel.org/all/20250221112003.1dSuoGyc@linutronix.de/

2 patch(es) applied to rtw-next branch of rtw.git, thanks.

7cbec00dc731 wifi: rtlwifi: add WQ_UNBOUND to alloc_workqueue users
9c194fe4625d wifi: rtw88: add WQ_UNBOUND to alloc_workqueue users

---
https://github.com/pkshih/rtw.git