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=-2.5 required=3.0 tests=MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT 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 55034C32789 for ; Tue, 6 Nov 2018 20:08:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 277212085B for ; Tue, 6 Nov 2018 20:08:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 277212085B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.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 S1727447AbeKGFfU (ORCPT ); Wed, 7 Nov 2018 00:35:20 -0500 Received: from mx2.suse.de ([195.135.220.15]:46258 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727268AbeKGFfU (ORCPT ); Wed, 7 Nov 2018 00:35:20 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id D5DA5B05C; Tue, 6 Nov 2018 20:08:24 +0000 (UTC) Date: Tue, 6 Nov 2018 21:08:23 +0100 From: Michal Hocko To: Arun KS Cc: arunks.linux@gmail.com, akpm@linux-foundation.org, vbabka@suse.cz, osalvador@suse.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, getarunks@gmail.com Subject: Re: [PATCH v6 1/2] memory_hotplug: Free pages as higher order Message-ID: <20181106200823.GT27423@dhcp22.suse.cz> References: <1541484194-1493-1-git-send-email-arunks@codeaurora.org> <20181106140638.GN27423@dhcp22.suse.cz> <542cd3516b54d88d1bffede02c6045b8@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <542cd3516b54d88d1bffede02c6045b8@codeaurora.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 06-11-18 21:01:29, Arun KS wrote: > On 2018-11-06 19:36, Michal Hocko wrote: > > On Tue 06-11-18 11:33:13, Arun KS wrote: > > > When free pages are done with higher order, time spend on > > > coalescing pages by buddy allocator can be reduced. With > > > section size of 256MB, hot add latency of a single section > > > shows improvement from 50-60 ms to less than 1 ms, hence > > > improving the hot add latency by 60%. Modify external > > > providers of online callback to align with the change. > > > > > > This patch modifies totalram_pages, zone->managed_pages and > > > totalhigh_pages outside managed_page_count_lock. A follow up > > > series will be send to convert these variable to atomic to > > > avoid readers potentially seeing a store tear. > > > > Is there any reason to rush this through rather than wait for counters > > conversion first? > > Sure Michal. > > Conversion patch, https://patchwork.kernel.org/cover/10657217/ is currently > incremental to this patch. The ordering should be other way around. Because as things stand with this patch first it is possible to introduce a subtle race prone updates. As I've said I am skeptical the race would matter, really, but there is no real reason to risk for that. Especially when you have the other (first) half ready. -- Michal Hocko SUSE Labs