From nobody Sun Feb 8 07:21:49 2026 Received: from SHSQR01.spreadtrum.com (mx1.unisoc.com [222.66.158.135]) (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 C077017C66 for ; Thu, 22 Feb 2024 07:29:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=222.66.158.135 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708586988; cv=none; b=l+dmFywaI08EvXE3AbXiXYO5Z0128JYgwDCzhCdDW6kuIZIhgRJgx0ada4TA2XBb2QZ7ZdHOxULABI4t2tfg3cC6jYTWaPCcFKggjO/RSc8zTVrR4FAeF7in15C6i0tTLQCz4Ou/IurPLAn2Qyh0y3RCe4DjMATlr+5A2DBocMU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708586988; c=relaxed/simple; bh=ZewFdUzDiW9tecGSCwjtH6I1LkrKq7cYVcOWOnxt2kw=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=UMGsngpNZjnpSECF6QJFjX8f28vtuLo6OO6Fi49FsnPPvayr6mZHh2mw947xwLcRMEzdYd2ynRPAyd20l9H8ZlNj/1Jsgg9apf1zbLWeLWxwLNa/MikivzQwn27sydrBnET17xsnZ/PJ1TKIgSvAg+XdU31/DohsMjAx5r/g+ls= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=unisoc.com; spf=pass smtp.mailfrom=unisoc.com; arc=none smtp.client-ip=222.66.158.135 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=unisoc.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=unisoc.com Received: from dlp.unisoc.com ([10.29.3.86]) by SHSQR01.spreadtrum.com with ESMTP id 41M7SqTQ091900; Thu, 22 Feb 2024 15:28:52 +0800 (+08) (envelope-from Xuewen.Yan@unisoc.com) Received: from SHDLP.spreadtrum.com (bjmbx01.spreadtrum.com [10.0.64.7]) by dlp.unisoc.com (SkyGuard) with ESMTPS id 4TgPrG70VJz2KL4Pp; Thu, 22 Feb 2024 15:28:14 +0800 (CST) Received: from BJ10918NBW01.spreadtrum.com (10.0.73.73) by BJMBX01.spreadtrum.com (10.0.64.7) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Thu, 22 Feb 2024 15:28:49 +0800 From: Xuewen Yan To: , CC: , , , , , , , , , Subject: [PATCH v2] workqueue: Control intensive warning threshold through cmdline Date: Thu, 22 Feb 2024 15:28:08 +0800 Message-ID: <20240222072808.5363-1-xuewen.yan@unisoc.com> X-Mailer: git-send-email 2.25.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: SHCAS03.spreadtrum.com (10.0.1.207) To BJMBX01.spreadtrum.com (10.0.64.7) X-MAIL: SHSQR01.spreadtrum.com 41M7SqTQ091900 Content-Type: text/plain; charset="utf-8" When CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel will report the work functions which violate the intensive_threshold_us repeatedly. And now, only when the violate times exceed 4 and is a power of 2, the kernel warning could be triggered. However, sometimes, even if a long work execution time occurs only once, it may cause other work to be delayed for a long time. This may also cause some problems sometimes. In order to freely control the threshold of warninging, a boot argument is added so that the user can control the warning threshold to be printed. At the same time, keep the exponential backoff to prevent reporting too muc= h. By default, the warning threshold is 4. Signed-off-by: Xuewen Yan --- changes of v2: -Update descriptions and fix some syntax errors in documentation. -Use threshold to limit the warnning and keep the exponential backoff.=20 --- --- Documentation/admin-guide/kernel-parameters.txt | 11 +++++++++++ kernel/workqueue.c | 14 +++++++++++--- 2 files changed, 22 insertions(+), 3 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index 31b3a25680d0..cde809b22eba 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -7225,6 +7225,17 @@ threshold repeatedly. They are likely good candidates for using WQ_UNBOUND workqueues instead. =20 + workqueue.cpu_intensive_warning_thresh=3D + If CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel + will report the work functions which violate the + intensive_threshold_us repeatedly. In order to prevent + the kernel log from being printed too frequently, + control the frequency and the threshold. + + By Default, the threshold is 4 times, and the warning + is limited by powers of 2. On the other hand, 0 will + disable the warning. + workqueue.power_efficient Per-cpu workqueues are generally preferred because they show better performance thanks to cache diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 7b482a26d741..606ba8bf5271 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -359,6 +359,10 @@ static const char *wq_affn_names[WQ_AFFN_NR_TYPES] =3D= { */ static unsigned long wq_cpu_intensive_thresh_us =3D ULONG_MAX; module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ul= ong, 0644); +#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT +static unsigned int wq_cpu_intensive_warning_thresh =3D 4; +module_param_named(cpu_intensive_warning_thresh, wq_cpu_intensive_warning_= thresh, uint, 0644); +#endif =20 /* see the comment above the definition of WQ_POWER_EFFICIENT */ static bool wq_power_efficient =3D IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DE= FAULT); @@ -1198,11 +1202,13 @@ static void wq_cpu_intensive_report(work_func_t fun= c) u64 cnt; =20 /* - * Start reporting from the fourth time and back off + * Start reporting from the warning_thresh and back off * exponentially. */ cnt =3D atomic64_inc_return_relaxed(&ent->cnt); - if (cnt >=3D 4 && is_power_of_2(cnt)) + if (wq_cpu_intensive_warning_thresh && + cnt >=3D wq_cpu_intensive_warning_thresh && + is_power_of_2(cnt + 1 - wq_cpu_intensive_warning_thresh)) printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu= times, consider switching to WQ_UNBOUND\n", ent->func, wq_cpu_intensive_thresh_us, atomic64_read(&ent->cnt)); @@ -1231,10 +1237,12 @@ static void wq_cpu_intensive_report(work_func_t fun= c) =20 ent =3D &wci_ents[wci_nr_ents++]; ent->func =3D func; - atomic64_set(&ent->cnt, 1); + atomic64_set(&ent->cnt, 0); hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func); =20 raw_spin_unlock(&wci_lock); + + goto restart; } =20 #else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ --=20 2.25.1