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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 9EBD4C4338F for ; Fri, 30 Jul 2021 06:36:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 852FC60F6B for ; Fri, 30 Jul 2021 06:36:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237501AbhG3Gg7 (ORCPT ); Fri, 30 Jul 2021 02:36:59 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:58594 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237278AbhG3Gg4 (ORCPT ); Fri, 30 Jul 2021 02:36:56 -0400 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 1311422254; Fri, 30 Jul 2021 06:36:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1627627011; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=CQoiuOtQizQ1P3NzC2UpgAVz64H8oYKXgC33uSSYg5k=; b=RqY0P6/UWT3A05JkuBUlU6MX5gX2+tBxO+oMt+xBtWSGC9B0O2+ZxXvVcM9J2gcUYzPmWo WBufMu0pwcbO9Doj9HG1t8jpQVV33vHQyMWccrpxKUuccTdFJQvG+VD2ze43GqTPyu2v40 5mvvNVtAPXKyCSGPxWsaMDEXkXs818A= Received: from suse.cz (unknown [10.100.201.86]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id A4633A3B8A; Fri, 30 Jul 2021 06:36:50 +0000 (UTC) Date: Fri, 30 Jul 2021 08:36:50 +0200 From: Michal Hocko To: Feng Tang 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, Dave Hansen Subject: Re: [PATCH v6 1/6] mm/mempolicy: Add MPOL_PREFERRED_MANY for multiple preferred nodes Message-ID: References: <1626077374-81682-1-git-send-email-feng.tang@intel.com> <1626077374-81682-2-git-send-email-feng.tang@intel.com> <20210728141156.GC43486@shbuild999.sh.intel.com> <20210729070918.GA96680@shbuild999.sh.intel.com> <20210729151242.GA42865@shbuild999.sh.intel.com> <20210730030502.GA87066@shbuild999.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210730030502.GA87066@shbuild999.sh.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 30-07-21 11:05:02, Feng Tang wrote: > On Thu, Jul 29, 2021 at 06:21:19PM +0200, Michal Hocko wrote: > > On Thu 29-07-21 23:12:42, Feng Tang wrote: > > > On Thu, Jul 29, 2021 at 03:38:44PM +0200, Michal Hocko wrote: > > [...] > > > > Also the > > > > semantic to give nodes some ordering based on their numbers sounds > > > > rather weird to me. > > > > > > I agree, and as I admitted in the first reply, this need to be fixed. > > > > OK. I was not really clear that we are on the same page here. > > > > > > The semantic I am proposing is to allocate from prefered nodes in > > > > distance order starting from the local node. > > > > > > So the plan is: > > > * if the local node is set in 'prefer-many's nodemask, then chose > > > * otherwise chose the node with the shortest distance to local node > > > ? > > > > Yes and what I am trying to say is that you will achieve that simply by > > doing the following in policy_node: > > if (policy->mode == MPOL_PREFERRED_MANY) > > return nd; > > One thing is, it's possible that 'nd' is not set in the preferred > nodemask. Yes, and there shouldn't be any problem with that. The given node is only used to get the respective zonelist (order distance ordered list of zones to try). get_page_from_freelist will then use the preferred node mask to filter this zone list. Is that more clear now? -- Michal Hocko SUSE Labs