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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 A723EC4338F for ; Wed, 28 Jul 2021 15:18:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8EA5760F91 for ; Wed, 28 Jul 2021 15:18:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237095AbhG1PSh (ORCPT ); Wed, 28 Jul 2021 11:18:37 -0400 Received: from mga05.intel.com ([192.55.52.43]:45424 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235457AbhG1PSf (ORCPT ); Wed, 28 Jul 2021 11:18:35 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10059"; a="298267581" X-IronPort-AV: E=Sophos;i="5.84,276,1620716400"; d="scan'208";a="298267581" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jul 2021 08:18:14 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.84,276,1620716400"; d="scan'208";a="475877135" Received: from shbuild999.sh.intel.com (HELO localhost) ([10.239.146.151]) by fmsmga008.fm.intel.com with ESMTP; 28 Jul 2021 08:18:11 -0700 Date: Wed, 28 Jul 2021 23:18:10 +0800 From: Feng Tang To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , David Rientjes , Dave Hansen , Ben Widawsky , linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Andrea Arcangeli , Mel Gorman , Mike Kravetz , Randy Dunlap , Vlastimil Babka , Andi Kleen , Dan Williams , ying.huang@intel.com Subject: Re: [PATCH v6 2/6] mm/memplicy: add page allocation function for MPOL_PREFERRED_MANY policy Message-ID: <20210728151810.GD43486@shbuild999.sh.intel.com> References: <1626077374-81682-1-git-send-email-feng.tang@intel.com> <1626077374-81682-3-git-send-email-feng.tang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 28, 2021 at 02:42:26PM +0200, Michal Hocko wrote: > On Mon 12-07-21 16:09:30, Feng Tang wrote: > > The semantics of MPOL_PREFERRED_MANY is similar to MPOL_PREFERRED, > > that it will first try to allocate memory from the preferred node(s), > > and fallback to all nodes in system when first try fails. > > > > Add a dedicated function for it just like 'interleave' policy. > > > > Link: https://lore.kernel.org/r/20200630212517.308045-9-ben.widawsky@intel.com > > Suggested-by: Michal Hocko > > Co-developed-by: Ben Widawsky > > Signed-off-by: Ben Widawsky > > Signed-off-by: Feng Tang > > It would be better to squash this together with the actual user of the > function added by the next patch. Ok, will do > > --- > > mm/mempolicy.c | 19 +++++++++++++++++++ > > 1 file changed, 19 insertions(+) > > > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > > index 17b5800b7dcc..d17bf018efcc 100644 > > --- a/mm/mempolicy.c > > +++ b/mm/mempolicy.c > > @@ -2153,6 +2153,25 @@ static struct page *alloc_page_interleave(gfp_t gfp, unsigned order, > > return page; > > } > > > > +static struct page *alloc_page_preferred_many(gfp_t gfp, unsigned int order, > > + struct mempolicy *pol) > > We likely want a node parameter to know which one we want to start with > for locality. Callers should use policy_node for that. Yes, locality should be considered, something like this? int pnid, lnid = numa_node_id(); if (is_nodeset(lnid, &pol->nodes)) pnid = local_nid; else pnid = first_node(pol->nodes); page = __alloc_pages(((gfp | __GFP_NOWARN) & ~__GFP_DIRECT_RECLAIM), order, pnid, &pol->nodes); if (!page) page = __alloc_pages(gfp, order, lnid, NULL); return page; > > +{ > > + struct page *page; > > + > > + /* > > + * This is a two pass approach. The first pass will only try the > > + * preferred nodes but skip the direct reclaim and allow the > > + * allocation to fail, while the second pass will try all the > > + * nodes in system. > > + */ > > + page = __alloc_pages(((gfp | __GFP_NOWARN) & ~__GFP_DIRECT_RECLAIM), > > + order, first_node(pol->nodes), &pol->nodes); > > Although most users will likely have some form of GFP_*USER* here and > clearing __GFP_DIRECT_RECLAIM will put all other reclaim modifiers out > of game I think it would be better to explicitly disable some of them to > prevent from surprises. E.g. any potential __GFP_NOFAIL would be more > than surprising here. We do not have any (hopefully) but this should be > pretty cheap to exclude as we already have to modify already. > > preferred_gfp = gfp | __GFP_NOWARN; > preferred_gfp &= ~(__GFP_DIRECT_RECLAIM | __GFP_NOFAIL) OK, will add. Thanks, Feng > > > + if (!page) > > + page = __alloc_pages(gfp, order, numa_node_id(), NULL); > > + > > + return page; > > +} > > + > > /** > > * alloc_pages_vma - Allocate a page for a VMA. > > * @gfp: GFP flags. > > -- > > 2.7.4 > > -- > Michal Hocko > SUSE Labs