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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 6F1ADC433F5 for ; Mon, 6 Sep 2021 06:37:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E51A16056B for ; Mon, 6 Sep 2021 06:37:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E51A16056B Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 519366B0071; Mon, 6 Sep 2021 02:37:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4C8966B0072; Mon, 6 Sep 2021 02:37:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3B6E06B0073; Mon, 6 Sep 2021 02:37:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0093.hostedemail.com [216.40.44.93]) by kanga.kvack.org (Postfix) with ESMTP id 303526B0071 for ; Mon, 6 Sep 2021 02:37:08 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id C24DA8249980 for ; Mon, 6 Sep 2021 06:37:07 +0000 (UTC) X-FDA: 78556191294.23.4740AD8 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by imf17.hostedemail.com (Postfix) with ESMTP id 5F71FF000090 for ; Mon, 6 Sep 2021 06:37:07 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id CA74F2007A; Mon, 6 Sep 2021 06:37:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1630910225; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=C18ucwuH+xJ590fcQPWTQo1wKpR5pILZsUHhaeFFJM8=; b=NQJNxXbGll03ANbTcVcmNA5GRE1HmZ8q8Gkbt8sMek82fcvVlXMxFNq8skistKpgpjAyFl ptCsa57t0u4Izkcuk8A6SGw5VPSP6VR/Cdm6uuxiUnB8PZPvFHFElwZASWjuaWujvQGPD0 XbzzL0owuRWs7ezDAcoUrEO7IcyHWK8= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 02B5DA3B8E; Mon, 6 Sep 2021 06:37:04 +0000 (UTC) Date: Mon, 6 Sep 2021 08:37:04 +0200 From: Michal Hocko To: yong w Cc: Tejun Heo , Jonathan Corbet , Andrew Morton , Vladimir Davydov , Thomas Gleixner , "Peter Zijlstra (Intel)" , Shakeel Butt , Roman Gushchin , alexs@kernel.org, Wei Yang , Hui Su , Stephen Rothwell , wang.yong12@zte.com.cn, Cgroups , linux-doc@vger.kernel.org, LKML , Linux MM , yang.yang29@zte.com.cn Subject: Re: [PATCH v2] mm: Add configuration to control whether vmpressure notifier is enabled Message-ID: References: <1629417219-74853-1-git-send-email-wang.yong12@zte.com.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 5F71FF000090 Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=suse.com header.s=susede1 header.b=NQJNxXbG; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf17.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com X-Rspamd-Server: rspam01 X-Stat-Signature: buh9ga7ez4edb33867sh6e4tjgkmgdge X-HE-Tag: 1630910227-238663 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat 04-09-21 18:41:00, yong w wrote: [..] > > It is not in conflict but runtime overhead reduction without more burden > > on the configurability is usually a preferred approach. > I agree with you.I had an idea that we use global variables to identify whether > there is event registration,however, global variables need to be > protected with locks. Have a look at static keys which are usual tool to provide effectivelly zero overhead disabled branch. -- Michal Hocko SUSE Labs