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=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 B7B75C433E6 for ; Tue, 5 Jan 2021 01:03:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8622C229C5 for ; Tue, 5 Jan 2021 01:03:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728856AbhAEBDT (ORCPT ); Mon, 4 Jan 2021 20:03:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:39980 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728450AbhAEBBX (ORCPT ); Mon, 4 Jan 2021 20:01:23 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6F4A32253A; Tue, 5 Jan 2021 01:00:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1609808401; bh=fLXC7Df1GHk9gRTDjHLdUfWBVUVc21PxXynDGsHCSJA=; h=From:To:Cc:Subject:Date:From; b=lrFYWah67bXQC7r7gB9Y14E6XdtxJ8I2dLRUFxiD0mDcCE1cLobcTPfrlkXuGxdv6 pW7hYXgUyevvQdY1tXQTYrzqH9AYwUQgz9yM43FCI7w9KLAVsVPJLbjdXT4/CK8cTS mArgPFKNNYbUtx3hbws9lEUSsWeDbbsnR5GPmlsht2MeSPxvV3fs6h/7XUemSY5cEC bODbuUenSTjK3X/NzoQrF1lwSFl/emxqUG+WpB7/amqMsM40DHGB5VKOynuR93rLxF e9AvAR3nHYoZx8c0qXA8e9B5POJjYYC6LZTu4uLJ+JgRRvCeqDYZwcaj5jjzey+lvq /IQAL32R894/w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Yunfeng Ye , Lai Jiangshan , Tejun Heo , Sasha Levin Subject: [PATCH AUTOSEL 4.19 1/8] workqueue: Kick a worker based on the actual activation of delayed works Date: Mon, 4 Jan 2021 19:59:52 -0500 Message-Id: <20210105005959.3954510-1-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 eef77c82d2e19..cd98ef48345e1 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -3554,17 +3554,24 @@ 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