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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 8B215C43381 for ; Mon, 11 Jan 2021 13:47:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5507E2222B for ; Mon, 11 Jan 2021 13:47:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731020AbhAKNri (ORCPT ); Mon, 11 Jan 2021 08:47:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:57630 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731169AbhAKNKY (ORCPT ); Mon, 11 Jan 2021 08:10:24 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id BB25F22AAF; Mon, 11 Jan 2021 13:09:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1610370584; bh=ZUPoPv1DrRYBjzg/5+aEgA4OUgxU5r7rYrliBWfzLgE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yo21lXNSFmADYwJ1wsAuj2G0w58HJ1w9ihDsvFtP6xXDNVzZc4emzEYs9AJjqYE1s UsriDVLSrds0JrGHHu3n+uVO9CMQKDCQNzozDYEuYOIwePgg92ZZXU5MrfpLn/PBXi C+ppe1bqWFTsB5Bx6afINnv2yiBAhcPO3xFolqos= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yunfeng Ye , Lai Jiangshan , Tejun Heo , Sasha Levin Subject: [PATCH 5.4 01/92] workqueue: Kick a worker based on the actual activation of delayed works Date: Mon, 11 Jan 2021 14:01:05 +0100 Message-Id: <20210111130039.226222908@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210111130039.165470698@linuxfoundation.org> References: <20210111130039.165470698@linuxfoundation.org> User-Agent: quilt/0.66 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Yunfeng Ye [ Upstream commit 01341fbd0d8d4e717fc1231cdffe00343088ce0b ] 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's wq when invoking alloc_workqueue(). this patch only kick a worker based on the actual activation of delayed works. Signed-off-by: Yunfeng Ye Reviewed-by: Lai Jiangshan Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin --- kernel/workqueue.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 4aa268582a225..28e52657e0930 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3718,17 +3718,24 @@ static void pwq_adjust_max_active(struct pool_workqueue *pwq) * is updated and visible. */ if (!freezable || !workqueue_freezing) { + bool kick = false; + pwq->max_active = wq->saved_max_active; while (!list_empty(&pwq->delayed_works) && - pwq->nr_active < pwq->max_active) + pwq->nr_active < pwq->max_active) { pwq_activate_first_delayed(pwq); + kick = true; + } /* * 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. In realtime scenarios, always kicking a + * worker will cause interference on the isolated cpu cores, so + * let's kick iff work items were activated. */ - wake_up_worker(pwq->pool); + if (kick) + wake_up_worker(pwq->pool); } else { pwq->max_active = 0; } -- 2.27.0