From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8354C2D0E4 for ; Tue, 17 Nov 2020 07:33:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 760BB222E8 for ; Tue, 17 Nov 2020 07:33:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725948AbgKQHdR (ORCPT ); Tue, 17 Nov 2020 02:33:17 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:7551 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725446AbgKQHdR (ORCPT ); Tue, 17 Nov 2020 02:33:17 -0500 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4CZyMx4LKyzhZb4; Tue, 17 Nov 2020 15:33:01 +0800 (CST) Received: from [10.174.176.199] (10.174.176.199) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.487.0; Tue, 17 Nov 2020 15:33:07 +0800 To: , , CC: Shiyuan Hu , Hewenliang From: Yunfeng Ye Subject: workqueue: Only kick a worker after thawed or for an unbound workqueue Message-ID: Date: Tue, 17 Nov 2020 15:32:56 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.176.199] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In realtime scenario, We do not want to have interference on the isolated cpu cores. but when invoking alloc_workqueue() for percpu wq on the housekeeping cpu, it kick a kworker on the isolated cpu. alloc_workqueue pwq_adjust_max_active wake_up_worker The comment in pwq_adjust_max_active() said: "Need to kick a worker after thawed or an unbound wq's max_active is bumped" So it is unnecessary to kick a kworker for percpu wq's when alloc_workqueue. this patch only kick a worker after thawed or for an unbound workqueue. Signed-off-by: Yunfeng Ye --- kernel/workqueue.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index c41c3c17b86a..80f7bbd4889f 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3696,14 +3696,16 @@ static void pwq_unbound_release_workfn(struct work_struct *work) } /** - * pwq_adjust_max_active - update a pwq's max_active to the current setting + * pwq_adjust_max_active_and_kick - update a pwq's max_active to the current setting * @pwq: target pool_workqueue + * @force_kick: force to kick a worker * * If @pwq isn't freezing, set @pwq->max_active to the associated * workqueue's saved_max_active and activate delayed work items * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. */ -static void pwq_adjust_max_active(struct pool_workqueue *pwq) +static void pwq_adjust_max_active_and_kick(struct pool_workqueue *pwq, + bool force_kick) { struct workqueue_struct *wq = pwq->wq; bool freezable = wq->flags & WQ_FREEZABLE; @@ -3733,9 +3735,10 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq) /* * Need to kick a worker after thawed or an unbound wq's - * max_active is bumped. It's a slow path. Do it always. + * max_active is bumped. */ - wake_up_worker(pwq->pool); + if (force_kick || (wq->flags & WQ_UNBOUND)) + wake_up_worker(pwq->pool); } else { pwq->max_active = 0; } @@ -3743,6 +3746,11 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq) raw_spin_unlock_irqrestore(&pwq->pool->lock, flags); } +static void pwq_adjust_max_active(struct pool_workqueue *pwq) +{ + pwq_adjust_max_active_and_kick(pwq, false); +} + /* initialize newly alloced @pwq which is associated with @wq and @pool */ static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, struct worker_pool *pool) @@ -5252,7 +5260,7 @@ void thaw_workqueues(void) list_for_each_entry(wq, &workqueues, list) { mutex_lock(&wq->mutex); for_each_pwq(pwq, wq) - pwq_adjust_max_active(pwq); + pwq_adjust_max_active_and_kick(pwq, true); mutex_unlock(&wq->mutex); } -- 2.18.4