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 94D94C64EB8 for ; Thu, 4 Oct 2018 14:51:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A82420877 for ; Thu, 4 Oct 2018 14:51:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5A82420877 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 S1727546AbeJDVou (ORCPT ); Thu, 4 Oct 2018 17:44:50 -0400 Received: from mx2.suse.de ([195.135.220.15]:54774 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727293AbeJDVot (ORCPT ); Thu, 4 Oct 2018 17:44:49 -0400 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 EB983AEA1; Thu, 4 Oct 2018 14:51:09 +0000 (UTC) Date: Thu, 4 Oct 2018 16:51:08 +0200 From: Michal Hocko To: Arun KS Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, boris.ostrovsky@oracle.com, jgross@suse.com, akpm@linux-foundation.org, dan.j.williams@intel.com, vbabka@suse.cz, iamjoonsoo.kim@lge.com, gregkh@linuxfoundation.org, osalvador@suse.de, malat@debian.org, kirill.shutemov@linux.intel.com, jrdr.linux@gmail.com, yasu.isimatu@gmail.com, mgorman@techsingularity.net, aaron.lu@intel.com, devel@linuxdriverproject.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, xen-devel@lists.xenproject.org, vatsa@codeaurora.org, vinmenon@codeaurora.org, getarunks@gmail.com Subject: Re: [PATCH v4] memory_hotplug: Free pages as higher order Message-ID: <20181004145108.GH22173@dhcp22.suse.cz> References: <1538573979-28365-1-git-send-email-arunks@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1538573979-28365-1-git-send-email-arunks@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 Wed 03-10-18 19:09:39, Arun KS wrote: [...] > +static int online_pages_blocks(unsigned long start, unsigned long nr_pages) > +{ > + unsigned long end = start + nr_pages; > + int order, ret, onlined_pages = 0; > + > + while (start < end) { > + order = min(MAX_ORDER - 1UL, __ffs(start)); > + > + while (start + (1UL << order) > end) > + order--; this really made me scratch my head. Wouldn't it be much simpler to do the following? order = min(MAX_ORDER - 1, get_order(end - start))? > + > + ret = (*online_page_callback)(pfn_to_page(start), order); > + if (!ret) > + onlined_pages += (1UL << order); > + else if (ret > 0) > + onlined_pages += ret; > + > + start += (1UL << order); > + } > + return onlined_pages; > } [...] > -static void __init __free_pages_boot_core(struct page *page, unsigned int order) > +void __free_pages_core(struct page *page, unsigned int order) > { > unsigned int nr_pages = 1 << order; > struct page *p = page; > unsigned int loop; > > - prefetchw(p); > - for (loop = 0; loop < (nr_pages - 1); loop++, p++) { > - prefetchw(p + 1); > + for (loop = 0; loop < nr_pages; loop++, p++) { > __ClearPageReserved(p); > set_page_count(p, 0); > } > - __ClearPageReserved(p); > - set_page_count(p, 0); > > page_zone(page)->managed_pages += nr_pages; > set_page_refcounted(page); I think this is wort a separate patch as it is unrelated to the patch. -- Michal Hocko SUSE Labs