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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 97FC7C0044C for ; Wed, 7 Nov 2018 06:19:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60BE520827 for ; Wed, 7 Nov 2018 06:19:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="LfREkMXd"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="LfREkMXd" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 60BE520827 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730256AbeKGPsj (ORCPT ); Wed, 7 Nov 2018 10:48:39 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:34132 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726353AbeKGPsj (ORCPT ); Wed, 7 Nov 2018 10:48:39 -0500 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id F004F6083C; Wed, 7 Nov 2018 06:19:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1541571584; bh=HvpLavO+GmYf9GHLQ65PRFffMVWFQXEE/f33R+iPmMQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LfREkMXdQzvQBxv/AnSTUnD6TeRc0bAYlgccZqCov+dCXpYJLXIx9Q2YeKRnYQTjH SBgQzv6l9h8pQpiNwlvqmQaUqSz+8XvrmSI/I5x51+IXlV4glRIxg+RJbfbN5OCX2w oC97fZZWHTK3+oJYNfBtcQo4L1H+R84RKMMafugw= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 3978A603D2; Wed, 7 Nov 2018 06:19:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1541571584; bh=HvpLavO+GmYf9GHLQ65PRFffMVWFQXEE/f33R+iPmMQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=LfREkMXdQzvQBxv/AnSTUnD6TeRc0bAYlgccZqCov+dCXpYJLXIx9Q2YeKRnYQTjH SBgQzv6l9h8pQpiNwlvqmQaUqSz+8XvrmSI/I5x51+IXlV4glRIxg+RJbfbN5OCX2w oC97fZZWHTK3+oJYNfBtcQo4L1H+R84RKMMafugw= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 07 Nov 2018 11:49:44 +0530 From: Arun KS To: Andrew Morton Cc: keescook@chromium.org, khlebnikov@yandex-team.ru, minchan@kernel.org, getarunks@gmail.com, gregkh@linuxfoundation.org, mhocko@kernel.org, vbabka@suse.cz, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v1 0/4]mm: convert totalram_pages, totalhigh_pages and managed pages to atomic In-Reply-To: <20181106162206.0f43c1eb16c3dd812bdadbdd@linux-foundation.org> References: <1540551662-26458-1-git-send-email-arunks@codeaurora.org> <20181106162206.0f43c1eb16c3dd812bdadbdd@linux-foundation.org> Message-ID: <33a9d26369468824e27de5a636e4e843@codeaurora.org> X-Sender: arunks@codeaurora.org User-Agent: Roundcube Webmail/1.2.5 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-11-07 05:52, Andrew Morton wrote: > On Fri, 26 Oct 2018 16:30:58 +0530 Arun KS > wrote: > >> This series convert totalram_pages, totalhigh_pages and >> zone->managed_pages to atomic variables. > > The whole point appears to be removal of managed_page_count_lock, yes? > > Why? What is the value of this patchset? If "performance" then are > any > measurements available? Hello Andrew, https://patchwork.kernel.org/patch/10670787/ In version 2, I have added motivation behind this conversion. Pasting same here, totalram_pages, zone->managed_pages and totalhigh_pages updates are protected by managed_page_count_lock, but readers never care about it. Convert these variables to atomic to avoid readers potentially seeing a store tear. I don't think we have a performance improvement here. Regards, Arun