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Thu, 11 Sep 2025 02:25:29 -0700 (PDT) X-Google-Smtp-Source: AGHT+IF2H+JPCFwbra3MAMOkZHX+Stii7EUBqUCAy+sBwWd6ZjwXiYMgQFhgrblInn0ElSZrVl05Fg== X-Received: by 2002:a05:6000:2c0c:b0:3e7:46bf:f89d with SMTP id ffacd0b85a97d-3e746bffe2dmr13867535f8f.44.1757582729043; Thu, 11 Sep 2025 02:25:29 -0700 (PDT) Received: from [192.168.0.115] ([216.128.11.130]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3e7607e2d43sm1694588f8f.59.2025.09.11.02.25.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Sep 2025 02:25:28 -0700 (PDT) Message-ID: <86200ee5-c0dc-4a70-823a-ae36b2e6c544@redhat.com> Date: Thu, 11 Sep 2025 11:25:27 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 3/3] net: WQ_PERCPU added to alloc_workqueue users To: Marco Crivellari , linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: Tejun Heo , Lai Jiangshan , Frederic Weisbecker , Sebastian Andrzej Siewior , Michal Hocko , "David S . Miller" , Eric Dumazet , Jakub Kicinski References: <20250905090505.104882-1-marco.crivellari@suse.com> <20250905090505.104882-4-marco.crivellari@suse.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: <20250905090505.104882-4-marco.crivellari@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 9/5/25 11:05 AM, Marco Crivellari wrote: > Currently if a user enqueue 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 consistentcy cannot be addressed without refactoring the API. > > 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 patch adds a new WQ_PERCPU flag at the network subsystem, to explicitly > request the use of the per-CPU behavior. Both flags coexist for one release > cycle to allow callers to transition their calls. > > Once migration is complete, WQ_UNBOUND can be removed and unbound will > become the implicit default. > > 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. > > All existing users have been updated accordingly. > > Suggested-by: Tejun Heo > Signed-off-by: Marco Crivellari This and patch 1/3 do not apply cleanly to the net-next tree. Please rebase and repost. Also I suggest to split the wireless bit out of this series and send them to the relevant sub tree, to avoid later merge issue. Thanks, Paolo