From patchwork Fri Sep 13 13:17:19 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: chenridong X-Patchwork-Id: 13803451 Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6C8811E892; Fri, 13 Sep 2024 13:25:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.190 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726233939; cv=none; b=KdhNOLykSY+Rip7KCc0CfwiLGfTUL/UU/3YQmiN1eBGwUqN6KC2Il+y+FqNpksHy+JWSi7QiS41gq0ATwJ1QZOExmZ+l/pj/VawAYg0mU/W3XyO0bK8+Tk4ySWMbzmnmCIkkRjJRotdr+ok61A+w8aliKdgc9pRIqIuoJPbCKe0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726233939; c=relaxed/simple; bh=jrkvQb9JHC+R7KVldUDHK5KkjrVybDN0XoN4ddqbUPY=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=T5txcDJmC8+QLATR9jaV6K9NK7QKWnglhQaoSTaq5p7OZr1Z3J6bR26jkOqwJkaJ5e1bhnoyUQnnNiJZS47JgPRFlLJuwmn9XxtGVgy7FGlJzD/PYcLhmh45m+6fckPSnvEbyl2PFMJvdJKMR69ahU13nIAYA4OhCdji/T/43gY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.44]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4X4w6F2wj6z20nvp; Fri, 13 Sep 2024 21:25:25 +0800 (CST) Received: from kwepemd100013.china.huawei.com (unknown [7.221.188.163]) by mail.maildlp.com (Postfix) with ESMTPS id A7D5A1402CD; Fri, 13 Sep 2024 21:25:33 +0800 (CST) Received: from huawei.com (10.67.174.121) by kwepemd100013.china.huawei.com (7.221.188.163) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.34; Fri, 13 Sep 2024 21:25:32 +0800 From: Chen Ridong To: , , , , , , , , , , , , , , , CC: , , Subject: [PATCH v4 2/3] workqueue: doc: Add a note saturating the system_wq is not permitted Date: Fri, 13 Sep 2024 13:17:19 +0000 Message-ID: <20240913131720.1762188-3-chenridong@huawei.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240913131720.1762188-1-chenridong@huawei.com> References: <20240913131720.1762188-1-chenridong@huawei.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemd100013.china.huawei.com (7.221.188.163) If something is expected to generate large number of concurrent works, it should utilize its own dedicated workqueue rather than system wq. Because this may saturate system_wq and potentially block other's works. eg, cgroup release work. Let's document this as a note. Signed-off-by: Chen Ridong --- Documentation/core-api/workqueue.rst | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/Documentation/core-api/workqueue.rst b/Documentation/core-api/workqueue.rst index 16f861c9791e..338b25e86f8c 100644 --- a/Documentation/core-api/workqueue.rst +++ b/Documentation/core-api/workqueue.rst @@ -356,6 +356,10 @@ Guidelines special attribute, can use one of the system wq. There is no difference in execution characteristics between using a dedicated wq and a system wq. + Note: If something is expected to generate large number of concurrent + works, it should utilize its own dedicated workqueue rather than + system wq. Because this may saturate system_wq and potentially block + other's works. eg, cgroup release work. * Unless work items are expected to consume a huge amount of CPU cycles, using a bound wq is usually beneficial due to the increased