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 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 860ECC32789 for ; Tue, 6 Nov 2018 15:31:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4A5E22081D for ; Tue, 6 Nov 2018 15:31:32 +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="fn9RoCgD"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="fn9RoCgD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4A5E22081D 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 S2388573AbeKGA5O (ORCPT ); Tue, 6 Nov 2018 19:57:14 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:33812 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387480AbeKGA5O (ORCPT ); Tue, 6 Nov 2018 19:57:14 -0500 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id BE8F0605A2; Tue, 6 Nov 2018 15:31:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1541518289; bh=dJCLvK0/kguUHSD0MooRrNkFPab6Uj49lc3hhpL3PqE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=fn9RoCgDZGU3rAT3J6hJdjbhDn7wJPoWnOQndF3XtskUi4ZvfqhfdFKXtbJmVELhn pgwpGSfghWx1HPen1mL+uRNCgC3qszOI7Yz19nOfM/098UhKjOUCZfm+Zfu7/KjmPL fOPxk3ruwlbHh7+hyiUTdaNz8jHUSwVjnOgEIpvo= Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 64E9C601D7; Tue, 6 Nov 2018 15:31:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1541518289; bh=dJCLvK0/kguUHSD0MooRrNkFPab6Uj49lc3hhpL3PqE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=fn9RoCgDZGU3rAT3J6hJdjbhDn7wJPoWnOQndF3XtskUi4ZvfqhfdFKXtbJmVELhn pgwpGSfghWx1HPen1mL+uRNCgC3qszOI7Yz19nOfM/098UhKjOUCZfm+Zfu7/KjmPL fOPxk3ruwlbHh7+hyiUTdaNz8jHUSwVjnOgEIpvo= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 06 Nov 2018 21:01:29 +0530 From: Arun KS 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 Subject: Re: [PATCH v6 1/2] memory_hotplug: Free pages as higher order In-Reply-To: <20181106140638.GN27423@dhcp22.suse.cz> References: <1541484194-1493-1-git-send-email-arunks@codeaurora.org> <20181106140638.GN27423@dhcp22.suse.cz> Message-ID: <542cd3516b54d88d1bffede02c6045b8@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 2018-11-06 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. I ll change the order. Will wait for preparatory patch to settle first. Regards, Arun. > > The patch as is looks good to me - modulo atomic counters of course. I > cannot really judge whether existing updaters do really race in > practice > to take this riskless. > > The improvement is nice of course but this is a rare operation and 50ms > vs 1ms is hardly noticeable. So I would rather wait for the preparatory > work to settle. Btw. is there anything blocking that? It seems to be > mostly automated.