From mboxrd@z Thu Jan 1 00:00:00 1970 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: 8bit Content-Type: text/plain X-ClientProxiedBy: SHCAS03.spreadtrum.com (10.0.1.207) To BJMBX01.spreadtrum.com (10.0.64.7) X-MAIL:SHSQR01.spreadtrum.com 41M7SqTQ091900 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 much. 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. --- --- 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/Documentation/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. + workqueue.cpu_intensive_warning_thresh= + 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] = { */ static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX; module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644); +#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT +static unsigned int wq_cpu_intensive_warning_thresh = 4; +module_param_named(cpu_intensive_warning_thresh, wq_cpu_intensive_warning_thresh, uint, 0644); +#endif /* see the comment above the definition of WQ_POWER_EFFICIENT */ static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT); @@ -1198,11 +1202,13 @@ static void wq_cpu_intensive_report(work_func_t func) u64 cnt; /* - * Start reporting from the fourth time and back off + * Start reporting from the warning_thresh and back off * exponentially. */ cnt = atomic64_inc_return_relaxed(&ent->cnt); - if (cnt >= 4 && is_power_of_2(cnt)) + if (wq_cpu_intensive_warning_thresh && + cnt >= 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 func) ent = &wci_ents[wci_nr_ents++]; ent->func = func; - atomic64_set(&ent->cnt, 1); + atomic64_set(&ent->cnt, 0); hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func); raw_spin_unlock(&wci_lock); + + goto restart; } #else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */ -- 2.25.1