Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753238Ab2KTCPV (ORCPT ); Mon, 19 Nov 2012 21:15:21 -0500 Received: from mail-oa0-f46.google.com ([209.85.219.46]:63896 "EHLO mail-oa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752496Ab2KTCPU (ORCPT ); Mon, 19 Nov 2012 21:15:20 -0500 Message-ID: <50AAE7B0.5000003@gmail.com> Date: Tue, 20 Nov 2012 10:15:12 +0800 From: Jaegeuk Hanse User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121028 Thunderbird/16.0.2 MIME-Version: 1.0 To: Jiang Liu CC: Andrew Morton , Wen Congyang , David Rientjes , Jiang Liu , Maciej Rutecki , Chris Clayton , "Rafael J . Wysocki" , Mel Gorman , Minchan Kim , KAMEZAWA Hiroyuki , Michal Hocko , Jianguo Wu , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFT PATCH v1 4/5] mm: provide more accurate estimation of pages occupied by memmap References: <20121115112454.e582a033.akpm@linux-foundation.org> <1353254850-27336-1-git-send-email-jiang.liu@huawei.com> <1353254850-27336-5-git-send-email-jiang.liu@huawei.com> In-Reply-To: <1353254850-27336-5-git-send-email-jiang.liu@huawei.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2533 Lines: 71 On 11/19/2012 12:07 AM, Jiang Liu wrote: > If SPARSEMEM is enabled, it won't build page structures for > non-existing pages (holes) within a zone, so provide a more accurate > estimation of pages occupied by memmap if there are big holes within > the zone. > > And pages for highmem zones' memmap will be allocated from lowmem, > so charge nr_kernel_pages for that. > > Signed-off-by: Jiang Liu > --- > mm/page_alloc.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 5b327d7..eb25679 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4435,6 +4435,22 @@ void __init set_pageblock_order(void) > > #endif /* CONFIG_HUGETLB_PAGE_SIZE_VARIABLE */ > > +static unsigned long calc_memmap_size(unsigned long spanned_pages, > + unsigned long present_pages) > +{ > + unsigned long pages = spanned_pages; > + > + /* > + * Provide a more accurate estimation if there are big holes within > + * the zone and SPARSEMEM is in use. > + */ > + if (spanned_pages > present_pages + (present_pages >> 4) && > + IS_ENABLED(CONFIG_SPARSEMEM)) > + pages = present_pages; > + > + return PAGE_ALIGN(pages * sizeof(struct page)) >> PAGE_SHIFT; > +} > + > /* > * Set up the zone data structures: > * - mark all pages reserved > @@ -4469,8 +4485,7 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat, > * is used by this zone for memmap. This affects the watermark > * and per-cpu initialisations > */ > - memmap_pages = > - PAGE_ALIGN(size * sizeof(struct page)) >> PAGE_SHIFT; > + memmap_pages = calc_memmap_size(size, realsize); > if (freesize >= memmap_pages) { > freesize -= memmap_pages; > if (memmap_pages) > @@ -4491,6 +4506,9 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat, > > if (!is_highmem_idx(j)) > nr_kernel_pages += freesize; > + /* Charge for highmem memmap if there are enough kernel pages */ > + else if (nr_kernel_pages > memmap_pages * 2) > + nr_kernel_pages -= memmap_pages; Since this is in else branch, if nr_kernel_pages is equal to 0 at initially time? > nr_all_pages += freesize; > > zone->spanned_pages = size; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/