From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f198.google.com (mail-pf1-f198.google.com [209.85.210.198]) by kanga.kvack.org (Postfix) with ESMTP id 3BC756B04BD for ; Wed, 7 Nov 2018 01:21:14 -0500 (EST) Received: by mail-pf1-f198.google.com with SMTP id g76-v6so282554pfe.13 for ; Tue, 06 Nov 2018 22:21:14 -0800 (PST) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.29.96]) by mx.google.com with ESMTPS id b12-v6si48301554pls.367.2018.11.06.22.21.13 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Nov 2018 22:21:13 -0800 (PST) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Wed, 07 Nov 2018 11:51:12 +0530 From: Arun KS Subject: Re: [PATCH v6 1/2] memory_hotplug: Free pages as higher order In-Reply-To: <20181106200823.GT27423@dhcp22.suse.cz> References: <1541484194-1493-1-git-send-email-arunks@codeaurora.org> <20181106140638.GN27423@dhcp22.suse.cz> <542cd3516b54d88d1bffede02c6045b8@codeaurora.org> <20181106200823.GT27423@dhcp22.suse.cz> Message-ID: <5e55c6e64a2bfd6eed855ea17a34788b@codeaurora.org> Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko 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 On 2018-11-07 01:38, Michal Hocko wrote: > 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. Makes sense. I have rebased the preparatory patch on top of -rc1. https://patchwork.kernel.org/patch/10670787/ Regards, Arun