From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754161Ab3KRTDb (ORCPT ); Mon, 18 Nov 2013 14:03:31 -0500 Received: from www.sr71.net ([198.145.64.142]:35496 "EHLO blackbird.sr71.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752730Ab3KRTD1 (ORCPT ); Mon, 18 Nov 2013 14:03:27 -0500 Message-ID: <528A6448.3080907@sr71.net> Date: Mon, 18 Nov 2013 11:02:32 -0800 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: Naoya Horiguchi CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org, dave.jiang@intel.com, akpm@linux-foundation.org, dhillf@gmail.com, Mel Gorman Subject: Re: [PATCH] mm: call cond_resched() per MAX_ORDER_NR_PAGES pages copy References: <20131115225550.737E5C33@viggo.jf.intel.com> <20131115225553.B0E9DFFB@viggo.jf.intel.com> <1384800714-y653r3ch-mutt-n-horiguchi@ah.jp.nec.com> <1384800841-314l1f3e-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1384800841-314l1f3e-mutt-n-horiguchi@ah.jp.nec.com> Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/18/2013 10:54 AM, Naoya Horiguchi wrote: > diff --git a/mm/migrate.c b/mm/migrate.c > index cb5d152b58bc..661ff5f66591 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -454,7 +454,8 @@ static void __copy_gigantic_page(struct page *dst, struct page *src, > struct page *src_base = src; > > for (i = 0; i < nr_pages; ) { > - cond_resched(); > + if (i % MAX_ORDER_NR_PAGES == 0) > + cond_resched(); > copy_highpage(dst, src); This is certainly OK on x86, but remember that MAX_ORDER can be overridden by a config variable. Just picking one at random: config FORCE_MAX_ZONEORDER int "Maximum zone order" range 9 64 if PPC64 && PPC_64K_PAGES ... Would it be OK to only resched once every 2^63 pages? ;) Really, though, a lot of things seem to have MAX_ORDER set up so that it's at 256MB or 512MB. That's an awful lot to do between rescheds.